back LCD menu
top LCD menu
It’s easy to set your camera to auto-bracket. The hardest part of this process is navigating a camera manufacturer’s menu. Once you find it – and do it several times – you won’t forget it.
Here’s how to do it on current Canon cameras – the steps are similar for other cameras but the buttons and menus vary.
First, set the number of frames made in each bracketed sequence. Press the Menu button. Use the main command dial (top) to cycle through the menus on the LCD screen (back) Go to the 4th tab (small camera) > 1st list and then the use the jog wheel (back) to select the 5th item. Press the set button to select it. Use the jog wheel to select the number of shots and press the set button once again. While 3 is the most commonly used, it’s not unusual to use 5 or even 7. Because 3 is the most commonly used number, it’s likely that once you set this, you’ll reset it infrequently.
Second, set the difference in exposure values between shots. Press the Menu button.
Use the main command dial (top) to cycle through the menus. Go to the 1st tab (large camera), 2nd list, 1st item. Use the set button to highlight this function and the command dial (top) to set the difference in exposure values, then press the set button again. Remember! Press the set button at the end of this – if you don’t these new settings won’t be saved.
Remember! Continue shooting in bracketed sequences as long as auto-bracketing is turned on. When you return to shooting single shots, turn auto bracketing off. If you don’t, one out of three exposures will be improperly exposed – because your camera is still bracketing exposure. The quickest way to turn auto bracketing off is to turn your camera off and on, which will turn auto-bracketing off on most cameras.
When auto bracketing is activated, on the display at the top of your camera you’ll see a series of bars indicating how many exposures will be made and at what exposure value.
What about exposure compensation? Use exposure compensation or not. Bracketing is extreme exposure compensation. All that matters is that you create multiple exposures that once combined render both excellent highlight and shadow detail.
For HDR exposures that are hand-held set your drive or burst mode to continuous; the fastest setting you have; One Shot is too slow.
For HDR exposures using a tripod, consider using a cable release and mirror lockup to further reduce camera motion.
Practice turning on and turning off auto-bracketing and it won’t seem nearly as complicated as the first time you do it and in time the habit will become so ingrained that you won’t have to think about it any more. But until turning auto-bracketing on and off becomes second nature, proceed carefully and methodically. The most common mistake is to turn it on and forget to turn it off.
Today’s cameras have the ability to generate HDR merges on the fly. The problem is that they produce JPEGs with a smaller gamut (lower saturation), lower bit depth (fewer shades of gray), and compression artifacts (noise and jagged edges) and they offer no control over the tone mapping process.
If you want a better HDR file, choose to make multiple bracketed Raw files, then merge and tone map them manually. Remember, aside from exposure settings, in camera settings that affect the look of your image have little or no affect on Raw files, which can be processed any way you want to process them.
In camera HDR JPEGs can offer a fast and convenient preview of potential HDR results. You can get the convenience of one and the quality of the other by setting your camera to produce both JPEG and Raw files simultaneously.
scenes like this won’t benefit from HDR
scenes like this may be made with 1 exposure but benefit from more
scenes like this require HDR
How many exposures do you need for HDR images?
It depends on the contrast ratio of the scene you’re photographing.
And, it depends on how many corners you’re willing to cut.
There is a case to be made for rendering all images with bracketed exposures. If the best data in a file is in the top stop of the dynamic range of a camera, then making one exposure per stop of dynamic range in the scene, each weighted to the top stop pf the camera (ETTR), will give you ideal data in every stop of the rendered scene, once the exposures are merged. So, ideally, you’d make one exposure per stop of dynamic range in the scene. In your first exposure place the shadows in the top stop of the histogram (to the right), without clipping. Then in subsequent exposures reduce exposure in one stop increments, making a new exposure each time, until the highlights are placed in the top stop without any clipping. Then stop.
Practically, you don’t need to make one exposure per stop of dynamic range in the scene because detail rendered by data in the middle of the histogram, though potentially not ideal, is perfectly usable. Here’s where theory can overtake practice. Test this yourself and find out whether using many more exposures is really worth the effort. In my own tests, I haven’t seen enough difference to make this a regular practice. If you can’t see a difference, then the difference doesn’t matter.
If data in or above the middle of the histogram is good enough, then some scenes will have so little dynamic range (one, two or three stops) that you only need one exposure. Remember to expose to the right to get the best data. Files like this will look over-exposed until they are processed. Once again, for these types of images, using more exposures and processing them with HDR software routines may actually cause problems like posterization.
Surprisingly, some images that look ‘normal’ and don’t seem to need HDR can actually benefit from additional exposures; images where shadows are close to the left of the histogram; the last three stops to the left have dramatically less data to render tonal values and are prone to excess noise and posterization.
For scenes that exceed the dynamic range of a camera sensor and can’t be captured without clipping in a single exposure, the number of exposures needed to render them depends on the contrast ratio of the scene – some need two, some three, some four, some five …
How about making more even exposures and bracketing in half stops? Theoretically this would work. In practice, you’re likely to find that using too many exposures causes some artifacts like excessive midtone compression and posterization.
The number of exposures you need also depends on the number of stops of difference you choose between exposures. Using exposures one and a half stops apart usually produces results just as good as those made with one stop apart. Using exposures with two or more stops of difference between them may cause posterization, which is most visible in smooth gradations, like skies. Using exposures less than one stop apart usually does not produce better results. In a few cases using too many exposures can produce artifacts like excessive midtone compression and sometimes posterization.
In the end the number of exposures you use matters because if exposures are too close or too far apart results will not be optimal, nevertheless the final number of exposures you need depends on both the scene you’re photographing and the camera you’re photographing it with.
October 18, 2016 | Leave a Comment |
How many shots do you need to make an HDR merge?
The most common answer is three.
The real answer is … it depends. First, it depends on the contrast ratio of the scene. Second, it depends on the exposure value (EV) increments you use between exposures. Third, it depends on the camera you use.
Many scenes only need 2 exposures. Most scenes need 3. Some scenes need 5. Only a few scenes need 7 or more.
How far apart in EV (exposure value) should separate exposures be?
1.5 stops. (Really any value between 1 and 2 stops.) While you won’t get better image quality if you use more shots separated by less exposure value (less than 1 stop), you also won’t compromise it. While you can also use higher increments (more than 2 stops) be careful – you may produce banding in smooth areas, particularly those with gradations.
Do you need to make HDR merges more frequently with some cameras and less with others?
Yes. Cameras that have a greater dynamic range can capture a higher contrast ratio and so don’t require HDR bracketing as frequently. While this can make a difference for images that would require two and occassionally three shots, for scenes with more extreme contrast ratios HDR merges will be necessary for all cameras.
What exposure mode should you use?
In a majority of cases, use Aperture priority mode (fixing aperture) to fix depth of field. If aperture changes dramatically between separate exposures, substantial changes in depth of field will most likely lead to a loss of focus in some image areas.
You can make exposures for HDR merges by bracketing ISO. Noise levels between exposures will be averaged. The final results will have more noise than the lowest ISO and less noise than the highest ISO.
You can also make exposures for HDR merges with shutter priority mode (fixing shutter speed). Try this when shutter speed drops so low that you can no longer eliminate motion blur, either because of subject motion or because you’re hand holding your camera. (But, use a tripod if you can.)
Do you need to use a tripod to make exposures for HDR merges?
No. By setting your camera to auto-bracket and making exposures in quick bursts you can eliminate the need to use a tripod for well lit scenes. Today’s HDR merging softwares do an excellent job of aligning separate exposures. However, in low light or when long exposures are desired using a tripod is usually necessary.
Today’s cameras (including smart phones) can create great looking HDR images on the fly, but to get optimum results it’s best to do this manually. In camera solutions render artifacted JPEGs and give you little or no control over how the results look. For optimum results, make separate Raw exposures and render them manually. While the technology at work is wizardry, this four step process is easy to practice. It’s an essential skill for all photographers.
Today’s fast burst auto-bracketing cameras combined with software alignment make hand held HDR possible. However, it’s recommended that whenever practical you use a tripod to eliminate any alignment issues between frames that might arise; it’s necessary if exposures are long.
HDR merges require multiple bracketed exposures. The goal is to produce at least one exposure with great highlight detail and another with great shadow detail. You may need additional exposures in between your lightest and darkest exposures to help smooth tonal transitions between shadows and highlights. The most common number of images used is three, because this is the default number for auto-bracketing on DSLRs. However, there is no ideal number of exposures for all scenes. Some scenes need as few as two, while others need as many as eight. In general, it’s best to have more than you need, not less. The wider the dynamic range of the scene the more exposures you’ll need. Make sure that separate exposures are between 1 and 2 EV (exposure value)(equivalent to one f-stop) apart. It’s typically recommended that you fix f-stop and change shutter speed to avoid depth of field issues, but other changes in EV will work.
Merge in Lightroom
After producing multiple bracketed exposures, the next step is to combine them with software into a single 32 bit file.
Simply select the exposures you wish to include (You don’t have to use them all.) and use the software of your choice. The software you use to merge exposures will compensate for alignment and ghosting, from motion of either camera or subject. (Lightroom and Photoshop do excellent jobs.)
Rather than rushing to render this file at the same time, save it – you may want to render it multiple times.
Process in Lightroom
As 32 bit files can’t be displayed or printed, the penultimate step is to render them into a new 16 bit file capable of being displayed and/or printed. This is a critical step that has the greatest effect on the look and feel of your images.
You can use the same software that you created a 32 bit file with or any HDR software. There are many HDR softwares to choose from; Lightroom, Photoshop, Photomatix, NIK’s HDR Efex Pro, Aurora, etc. While most HDR softwares are capable of producing fine results (if used carefully), they do not all produce the same results. It’s worth comparing multiple products before settling on your favorite. You may even want to combine the renderings from different softwares in Photoshop.
Refine in Photoshop
Consider the purpose of the first HDR rendering of an image as a way to create a great base for further improvements. Even in the best HDR renderings, it’s rare that additional post-processing isn’t recommended. This could be as simple as reducing noise or as extensive as dodging and burning. In a few cases, you may even want to use Photoshop’s layers to blend multiple renderings of the same image.
Today’s cameras and software continue to make HDR merges easier and easier. You can get great benefits for just a little effort.
1 EV is equivalent to 1 F-Stop of brightness
These Contrast Ration (CR) figures are approximate
Today, many people think HDR refers to the practice of merging bracketed exposures with software, but HDR actually applies to everything in an imaging workflow – capture, processing, display, and printing.
What is HDR? HDR is an acronym that stands for High Dynamic Range. It’s the opposite of LDR or Low Dynamic Range Imaging.
What is dynamic range? In imaging, dynamic range (DR) is the highest overall level of contrast found in an image. In other fields, such as in the audio industry, dynamic range is used to describe similar phenomena. In audio, DR is defined as the logarithmic ratio between the largest readable signal and background noise. DR is akin to signal-to-noise ratio. In imaging, DR refers to the entire image. Consider an image a signal – and every signal has some noise.
The values used to specify dynamic range can be charted on multiple scales. Whatever language is used to describe this phenomenon, two critical factors must be addressed; the total range of brightness and the fineness of the steps used within the scale.
Two scales are most useful for images – exposure value and contrast ratio. Exposure value (EV) is easier to use while contrast ratios better display logarithmic increases in light intensities. Both refer to the same phenomenon – relative increase or decrease in brightness.
The EV scale makes it easy to compare the ratios rather than the big numbers of logarithmic progressions; each successive EV rating represents a doubling of values. The exposure value (EV) scale has been used by photographers for ages. The International Organization for Standards (ISO) defines EV 0 at an aperture size of 1 and a 1 second exposure time. The same EV can be achieved with any other combination of fstop and shutter speed that produces the same amount of light.
‘The contrast ratio scale specifically delineates values; when you use this rating you instantly see how much greater each step in a progression is than the previous one because the numbers are so much bigger. You can convert EV to contrast ration or vice versa with the right formulas. 2 (power of EV) = contrast ratio (2*8=256 for a contrast ratio of 256:1) or EV=log10(contrast ratio)*3.32 (log10(4000)*3.32=12EV
Dynamic range, gamut, and bit-depth are often confused. Though related, they’re all different. Dynamic range refers to a total range of luminosity values. Gamut refers to a total color capacity, including saturation. Bit depth refers to the number of points of data between values or the fineness of the increments in the scale. Just because an image is wide gamut doesn’t mean it is HDR or has high bit depth, but it will contain more and potentially better data if it does. Just because an image is HDR doesn’t mean it is wide gamut and has high bit depth, but it will contain more and potentially better data if it does. You can’t convert low dynamic range, small gamut, low bit depth information to high bit depth, wide gamut, high dynamic range information. To get it and use it, you have to capture high quality information upon exposure and preserve it throughout your workflow.
How the Eye Sees
In many ways, the human eye is inherently HDR. The human eye can see a contrast ratio of up to 1:10,000 or 14 EV at any one time. And, it can adapt to varying amounts of light, extending that contrast ratio to almost 1: 100,000,000. The eye has a physical response (pupils dilate) and an incredible sensitivity (as few as 30 photons). The eye (like all of our senses) has a nonlinear response; the power of a signal needs to increase logarithmically to produce a response twice as strong. So, highlights are naturally “compressed”. The eye has local adaptation; it applies different sensitivities to different regions in our visual field of view. This last ability is extraordinarily complex. The eye is not a completely separate organ but rather an integral part of our brain. Perception is always accompanied by interpretation. Perceiving value is a coordinated construction process that considers shape, color, light, and filtration. This happens subconsciously and cannot be prevented – but you can become more aware of it. At this point physics, biology, psychology, and philosophy all intersect.
How the Camera Sees
The camera eye is not HDR, yet. While tomorrow’s cameras may become inherently HDR, today’s camera’s can be used to produce HDR images with software. Like the human eye, film has a nonlinear response to light. For film we adjust the EV to fit the amount and contrast ratio of the available light into the most useful area of its curve response. Using film, you expose generally and when compromises need to be made you favor shadows or highlights. Details lost at the point of capture are irrecoverable.
Unlike the human eye, CCDs have a linear response to light. It simply counts photons, with no scaling. Consequently, in linear capture (Raw) half the data in the file is contained in the top EV of the tonal scale and the quality of the data in the lowest EVs is comparatively poor (susceptible to noise and banding). Raw files without conversion look very dark. When converted a tone curve is applied (gamma encoded) to make them appear normal. The images are mapped to an output referring standard.
Today, camera capture, film and CCD, offer roughly 8 EV compared to the eye’s 14 EV. Tomorrow, in this fast evolving field, the EV of photographic capture will be much higher, higher than today’s software solutions offer, and quite possibly even higher than the capabilities of the human eye.
HDR Software – Merges
Comparatively recent advances in software technology allow us to combine the data from multiple bracketed exposures into a single file. Here’s the fundamental difference between a single Raw file and an HDR file created from multiple Raw files. A Raw file captures the scene as a sensor sees it. An HDR file captures the full values of the scene. You can “reexpose” this HDR scene digitally as often as you like by taking a snapshot of it and developing an LDR image for output.
Rather than applying output referring gamma curves to an image, you choose how the tonal values are rendered. Tone mapping takes a scene referred to an output referred state. Once merged into an HDR image, exposure becomes adjustable; you can select any single exposure or any combination of all of the exposures; you can even do this selectively.
The extra data gives you astonishing fidelity and flexibility. You lock into a solution only when you render the image to LDR. If you preserve the HDR image, you can always return to it and rerender it, in another way, at another time. HDR is essentially not bound to the limits of a capture device or an output referring rendering.
HDR merges use 32 bit editing spaces to hold all the data contained in multiple 16 bit bracketed exposures. Creating an HDR file from 16 bit (65,536 shades of gray) capture does not create a true 32 bit (4,294,967,296 shades of gray) file. Few capture devices today deliver a full 16 bits of data. Software, like Photoshop, use 16 bit editing spaces to hold data over 8 bit (256 values). (As an aside, for complex coding reasons, a 16 bit file in Photoshop actually offers 15 bits of data plus 1 value or 32,768+1.) 32 bit file sizes are twice as large as 16 bit files (4 times as large as 8 bit files).
Adjustments made to high bit data display fewer artifacts, but, whether significant or insignificant, there are artifacts nonetheless. Tweak more and you continue to lose values and encounter rounding errors, possibly producing noise and banding. Raw files adjust the appearance of a file during conversion to a gamma encoded color space. Whether 8 or 16 bit, these are still LDR solutions; only whole values exist (128 or 129). HDR floating point solutions allows for decimals (128.1 or 128.15)(You can split the bit.) providing a near infinite number of values. No gamma is needed because you can get finer levels whenever you need them. Image data can then stay in linear space, unchanged by our perception of them. The upper and lower limits disappear. You can assign any value to any pixel and then adjust the relative relationships of other values to it. Depending on how a tonal structure is mapped, values may stray out of the histogram – what’s being used – but they are never lost.
As there are currently no 32 bit devices, 32 bit files must be rendered (interpreted) to be seen.
Currently, viewing HDR images is challenging. We use LDR monitors, LCD monitors achieve 9 EV, which can give us only a limited preview of the total data contained in an HDR file. However, technology is constantly advancing. Canon/Toshiba SED monitor technology offers 17 EV (or 1:100,000) and Brightside LCD/LED combination monitor technology offer an EV of 18 (or a contrast ration of roughly 1:200,000). What will tomorrow’s monitors look like?
Images in print are limited to roughly 6 EV. You can move the smaller window of the printable DR up or down within the larger captured DR; the larger that captured DR the more flexibility you have. HDR offers more options in print. It doesn’t offer higher dynamic range print materials. It’s difficult to create a surface that reflects less than 1% of the light it receives and impossible to create a surface that reflects 100% – though light emitting substrates exist today and will become increasingly available tomorrow. Many new technologies are starting to expand the 6 EV in print limit. There’s still a great deal of room for improvement before we catch up to the eye’s 12 EV.
HDR Is About Creative Control
How far do you want to go with HDR? It’s really up to you. But, you probably don’t want to go as far as you might think. As the brain tries to decode reflected light based on what it sees, extreme ranges of illumination may hinder rather than help perception. The artist who removes excess dynamic range in an image may actually make it easier for you to see the scene, than if you had to view and interpret it. To a large extent, finished images are already fully interpreted. HDR imaging techniques do more than solve technical challenges, they also give you the greatest freedom of interpretation. HDR technology and practices give you maximum control over the look and feel of your images.
HDR imaging (sensors, processing, and viewing) is the future of photography; it has been since the invention of photography and it continues to be today.
July 27, 2016 | Leave a Comment |
There are many things you can do in Photoshop to make the most of shadow and highlight detail in images, even if you didn’t bracket exposures for HDR.
Curves, the most precise tool for modifying brightness and contrast, allows you to target and adjust shadows and highlights independently of one another. You can use it to reduce contrast and render more detail in very bright highlights and/or very dark shadows. The Curves interface has a feature (The icon looks like a finger with up and down arrows.) that allows you to click on any area of an image to place a point and adjust those values. If you’re adjusting highlights and shadows, it’s quite likely that you will also have to adjust values in the other end of the tonal scale and possibly midtones to generate the best results. Keep it simple; it’s surprising what you can do with just two or three points. Keep it smooth; avoid posterization by not flattening areas of a curve. The Blend Mode Luminosity can be used to remove any unintended shifts in saturation; more contrasti increases saturation while less contrast decreases saturation.
Curves can be used to lighten shadows and/or darken highlights
The Shadow / Highlight feature in Photoshop (Image > Adjustments > Shadow Highlight) can be very useful for more challenging images. It cannot be applied as an adjustment layer but it can be applied as a smart filter. To preserve future flexibility, apply Shadows / Highlights applied to the Background Layer converted to a smart object or to a duplicate Background layer if you plan to use Blend If sliders.
At first glance, Shadows/Highlights appears to offer two simple Amount sliders. Check Show More Options and you’ll find more sliders. The Tonal Width slider specifies which values are and are not affected, similar to a luminance mask. The Radius slider applies a sharpening affect, similar to High Pass filtration, to the affected areas only; this is the slider that does what no other tool does. Additionally, you can apply Color and Midtone adjustments – but there are other better ways to do this.
The Radius slider in Photoshop’s Shadows/Highlights provides affects not found in other tools
Screen / Multiply
You can make industrial strength adjustments to an image using the Blend Modes Multiply and Screen found in the Layers palette. (Use the pull down menu that defaults to Normal.) Multiply dramatically darkens an image; it’s like registering two transparencies on a light table. Screen dramatically lightens an image; it’s like registering two projected images on a wall. These effects can be very helpful in making very bright highlight and very dark shadow detail more visible. Blend modes can be applied with any layer. They can be combined with Curves adjustments for even stronger effects. Because their effects are so strong you’ll want to modify their intensity using the Opacity slider or restrict their effects using Blend If sliders or a contrast mask.
Blend If Sliders
To restrict an adjustment to either the shadows, midtones, or highlights, you can use the Blend If sliders found in the Layer Style menu. Double click on the layer (Not the icon or the name, but the area to the right of them.) to activate the Layer Style menu. Then use the sliders in This Layer to remove the effect on the background layer. For smoother transitions, feather the effect by holding the Option/Alt key and splitting the sliders apart.
T Layer Style dialog with Blend If sliders set to target shadows
The Layer Style dialog with Blend If sliders set to target highlights
To more precisely target a specific range of the tonal scale, you can quickly make precise luminance masks in Photoshop. Simply go to the Channels palette and Command/Control click on the RGB channel. This will load a selection of the highlights. If you want to create a selection of the shadows go to the Select menu and choose Inverse. Then simply make an adjustment layer and the selection will automatically become a mask or target a layer and click the mask icon at the bottom of the Layer palette. You can further modify the brightness and contrast of the mask by applying Curves to it (Image > Adjust > Curves).
Do you still want more? If dynamic range issues persist in one channel (or even two), you can use the information in the other channel(s) to improve it. Use Photoshop’s Channel Mixer or use a duplicate layer’s Layer Styles. It’s a complex technique, but it’s there when you really need it.
For even more dramatic effects these methods can be used in combination with one another.
To Merge Or Not To Merge
All of this might make you wonder why you’d ever need to bracket exposures for HDR merges. Actually, there are plenty of times – when the dynamic range of a scene far exceeds the dynamic range of a camera’s sensor. You can use all of these techniques in combination with HDR merges to get optimum results. Knowing why and why not to use HDR merges, when and when not to use them, and how far to go or not go with them will help you master them.
Two exposures blended
The layer stack
Sometimes Two Exposures Are Optimum
There are a variety of ways to extend the dynamic range of a camera. The four classic ways are selective adjustment, double processing a single file, layering two exposures, and merging multiple exposures with HDR software routines.
Layering two exposures produces the best results when a scene has areas of dramatically different brightness separated by clear contours, like but not limited to horizons. For these types of scenes, layering two exposures avoids artifacts that are common in HDR merges, such as saturation distortions, midtone compression, localized vignetting, and detail / noise exaggeration artifacts.
Make Two Exposures Each Optimized For Select Areas
To exceed the dynamic range of a camera’s sensor (or film) you need to make at least two exposures. During exposure(s), rather than rather than striking a compromise between very different brightness values, instead optimize one exposure for each area of brightness, the highlights and the shadows. For each area, expose to the right. Monitor clipping differently. The exposure for the highlights will be clipped in the shadows. The exposure for the shadows will be clipped in the highlights. (If this is not the case, then you may be able to use a simpler technique such as selective adjustement or double processing.)
For this technique you only need two exposures, a very dark and a very light one, but to be on the safe side, make additional exposures in between them. It doesn’t matter which end of the tonal scale (dark or light) you start with. Simply work your way up or down from one to the other. Remember, using a tripod, locking down zoom lenses, and turning off auto focus will all help you register the two exposures more easily.
Process the Two Files Independently
Process the two exposures independently to optimize brightness and contrast separately. In most cases, you’ll want to render color temperature and saturation consistently between the two versions.
Make Each Exposure A Photoshop Layer In A Single File
You can use layers in Photoshop to combine the best information from both light and dark files. Simultaneously highlight the two files you want to use and create layers in Photoshop. Using Lightroom, go to Photo > Edit In > Open as Layers in Photoshop. Using Bridge, go to Tools > Photoshop > Load Files Into Photoshop Layers.
If you want to use Smart Objects, using Lightroom or Camera Raw, open the files separately as Smart Objects into Photoshop. In Lighroom go to Photo > Edit In > Open as Smart Object in Photoshop. In Camera Raw hold the Option/Alt key to Open Object. Then, holding the Shift key to register them, drag one image into the other. It doesn’t matter which layer you place on top. What matters is how you blend the two.
Registering The Two Layers
If you’ve used a tripod during exposure the two files will register instantly. If you’ve hand-held during exposure, they may not. If the layers don’t register you can highlight both layers and choose Edit > Auto-Align Layers. Alternately, use the Move tool and arrows to align the layers manually. Change the blend mode of the top layer to Difference and you’ll see lines around contours, which will disappear when the two layers are perfectly aligned.
Adjust The Mask
Double click on the layer mask and you’ll be able to access the Properties panel, which will allow you to refine the mask. The Feather slider will allow you to soften the edge, but be cautious if you do this as too high a setting will create a soft-edged halo. Click the Refine : Select and Mask and you’ll reveal more options, including the Shift Edge slide, which will allow you to reposition the mask’s contour.
In some cases, light spill or a soft haze of light may extend over the horizon. This may require selective adjustment. Adjust your mask accordingly.
The Properties panel for the layer mask
Adjust The Mix
Once the best blend is achieved, you can further enhance it with adjustment layers. Curves and Hue/Saturation are the two most useful types of adjustments.
To affect both layers withone adjustment, simply highlight the top layer and create an adjustment layer. To affect the bottom layer only, first highlight it and second create and adjustment layer, above it and below the top layer. To affect the top layer only, first highlight it and when you create the adjustment layer check the box for Use Previous Layer to Create Clipping Mask. (If you’re using the adjustment layer icon at the bottom of the Layers panel, to access this dialog box, hold the Option/Alt key before creating the adjustment layer.) You can clip or unclip an adjustment layer to a layer at any time by holding down the Option/Alt key and clicking on the line between them in the Layers panel.
Use a flexible workflow. Keep your layer stack in tact during editing and when you save your file (as a TIFF or PSD) to preserve your ability to make future improvements. Don’t flatten.
Be As Dramatic As You Want To Be
Using this technique difficult shooting conditions will become much easier for you. Many more image making opportunities will become available to you. It’s well worth investing the time to master these techniques as the versatility they will afford you will be both rewarding and profitable.
The images you create with this technique can be quite dramatic. They can exceed the dynamic range of cameras and sometimes even the human eye. You’ll be challenged to see in new ways. It’s your choice to render realistic or hyper-realistic results. Whatever you choose, your images will provide you and your viewers with a new window on the world.
1 exposure – scenes like this won’t benefit from HDR
3 exposures – scenes like this may be made with 1 exposure but benefit from more
5 exposures – scenes like this require HDR
How many exposures do you need for HDR images?
It depends on the contrast ratio of the scene you’re photographing.
Ideally, you’d make one exposure per stop of dynamic range in the scene. In your first exposure place the shadows in the top stop of the histogram (to the right), without clipping. Then in subsequent exposures reduce exposure in one stop increments, making a new exposure each time, until the highlights are placed in the top stop without any clipping. Then stop. Making more exposures is unnecessary and won’t improve image quality.
Some scenes have so little dynamic range (one, two or three stops) that you only need one exposure. (Remember to expose to the right to get the best bit depth.) For these types of images, using more exposures and processing them with HDR software routines may actually cause problems like posterization.
Surprisingly, some images that look ‘normal’ and don’t need HDR can actually benefit from additional exposures; images where shadows are close to the left of the histogram; the last three stops to the left have dramatically less data to render tonal values and are prone to excess noise and posterization.
For scenes that exceed the dynamic range of a camera sensor and can’t be captured without clipping in a single exposure, the number of exposures needed to render them depends on the contrast ratio of the scene – some need two, some three, some four, some five …
The number of exposures you need also depends on the number of stops of difference you choose between exposures. Using exposures one and a half stops apart usually produces results just as good as those made with one stop apart. Using exposures with two or more stops of difference between them may cause posterization, which is most visible in smooth gradations, like skies. Using exposures less than one stop apart usually does not produce better results and in a few cases using too many exposures can produce artifacts similar to using two few exposures.
In the end the number of exposures you use matters because if exposures are too close or too far apart results will not be optimal, nevertheless the final number of exposures you need depends on the scene you’re photographing.
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