1_Left

Left

2_Right

Right

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Panoramic stitches combine both

Think Outside The Frame

No one needs to learn to “think outside the box” more than photographers. The frame, literally a box, is often our greatest ally. Learning to see photographically is in part learning to see within the limits of this box and use them creatively. But there are times when this limits our vision unnecessarily. Once we’ve learned to see within the box, we then need to learn to also see outside the box – and start extending the frame with multiple exposures to perfect select compositions. Extending format techniques aren’t just for panoramic image formats. They can be used to give you the extra inch that can make all the difference in the world for your compositions.

Hand-held Exposure Techniques

While the best way to make exposures for panoramic merges is to use a dedicated panoramic head on a tripod, this may not be practical – or necessary. (There are three significant benefits to using panoramic tripod heads; one, they keep the camera level and without rotation throughout an exposure sequence, two they calculate the number of and overlap between exposures, and three they pivot the camera around a lenses nodal point minimizing parallax.) Today’s software packages work miracles making what was once impossible possible. Several practices can help you make better hand-held exposures for panoramic merges.

Keep the horizon level in all the exposures; varying rotation can cause improper alignment and/or excessive cropping and/or retouching.

Shoot a little loose. Perspective correction in these types of photo merges often resulting in irregular borders that beg cropping – or retouching, if this is appropriate. The extra wiggle room you gain from shooting loose will allow you to crop the final results more precisely.

Don’t shoot the separate exposures edge to edge. Instead, overlap your exposures by a third for medium lenses, a half for wide-angle lenses, and two thirds for fisheye lenses.

Make exposures with the opposite orientation as the final image orientation; if you’re making a horizontal composition shoot with a vertical camera orientation and if you’re making a vertical composition shoot with a horizontal camera orientation. This does two things. One, it increases the number of frames, and thus vanishing points, reducing the tendency for the required perspective correction to produce distortion artifacts. Two, it increases resolution – a tendency that becomes compounded with each added pass in multi-column or multi-row exposure sequences.

Once focus is set, turn off auto-focus during the bracketing sequence. Unwanted shifts in focus may ruin an exposure sequence. For this same reason, consider shooting all exposures in a single sequence at the same aperture setting, as significant variances in depth of field between frames may be challenging to merge convincingly.

Consider using manual exposure. While software can convincingly blend exposures with significantly varying exposures, if brightness across a scene remains fairly constant keeping the same exposure settings between different shots can aid the blending process. (The same is true for white balance, which can be set either during exposure or during Raw processing.) On the other hand, if brightness varies dramatically, bear in mind that simultaneous HDR exposure bracketing is not out of the question; it just increases the number of exposures needed.

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Lightroom’s Panorama Merge Preview

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Auto Crop checked

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Boundary Warp slid to 100

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Adobe Camera Raw’s Panorama Merge Preview

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Auto Crop checked

ACR_BoundaryWarp

Boundary Warp slid to 100

Stitching / Merging

Merge to Panorama in Lightroom and Adobe Camera Raw

You can perform panoramic merges in either Adobe Lightroom or Camera Raw. Their interfaces may look different but they’re the same.

There are three advantages to making panoramic merges with these Raw converters. First, it creates a new combined file in DNG format and allows future access to the Raw data in the files. Second, they offer simple but powerful post-merge distortion (Boundary Warp) and Auto Crop options that Photoshop’s Photomerge doesn’t. (This means you’d only choose Photoshop when you wanted to use its additional merge projection options Collage and Reposition.) Third, the DNG file takes up less space than the PSD or TIFF file Photoshop generates.

How do you do this?

Read more

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Combine 3 or more exposures into 1

MergedOut_Mean

Remove moving objects using Photoshop's Smart Objects

Use the Stack Mode Mean

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Keep moving objects using Photoshop's Smart Objects

Use the Stack Mode Minimum

It’s a perfect shot! If only those unwanted objects (cars, birds, people, etc) in the scene would disappear. As long as the unwanted elements in your frame move, even just a little, you can make them disappear from your image, by taking two or more shots and using Photoshop’s layering and blending capabilities.

You don’t have to retouch your image. Blending is different than retouching. The unwanted elements aren’t covered over with new information, by hiding them with replacement information similar to the surround, either from the same source or another. With blends, the information behind the moving subject is revealed. How? It’s contained in the other shot(s).

You can even do this with exposures that are made with slightly different angles of rotation or framing, so you can use this technique with handheld exposures, not just those made with a tripod. Camera motion may make manual registration difficult, but Photoshop will automatically align and in some cases distort the separate exposures so that they register precisely. In some of these cases, you may need to crop the final result to restore a rectangular frame.

You can even remove stationary objects with blends – if you move. In situations where there is sufficient parallax between foreground and background elements, by varying your angle of view, you can cause significant shifts in position of foreground elements without causing significant changes in position of background elements. Make multiple exposures from multiple angles of view and you can blend out the elements that appear to move. When using this technique, shoot loose, planning to crop more after the merger.

If you have only two exposures you’ll need to manually mask the top layer. If you have three or more layers Photoshop will automatically blend the layers.

So how do you do this with Photoshop?


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Foreground in focus

1_front

Background in focus

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Two exposures combined to achieve infinite depth of field

How deep would you like your depth of field to be? The choice is yours. Today, there are virtually no limits. You can extend depth of field beyond the physical limitations of any lens/camera system with multi-shot exposure practices and software – by compositing multiple exposures.

To do this you first need to make a set of focus bracketed exposures, optimizing focus in different image areas. How many exposures you’ll need will depend on how much depth of field a scene contains. At a minimum, make two exposures; one focused on the foreground and another focused on the background. Making three exposures is better; one each for foreground, middle ground and background. When dealing with extreme depth of field, like macro or microphotography, you’ll want to make more exposures, at least three, probably six, possibly more. When in doubt, make more exposures than you think you’ll need; you don’t have to use them all when you stack the separate exposures, but they’ll be there if you need them. Unlike bracketing for HDR, it’s almost impossible to automate these types of bracketing sequences in camera as focus needs to be adjusted for each frame. However, for tethered shooting, you can use software such as Helicon Remote to take control of your camera and automate this process and other bracketed sequences like HDR and time-lapse. Whenever possible use a tripod to make focusing during exposure more precise and registration during post-processing easier. While using a tripod always delivers more reliable results, don’t let this stop you from trying this technique hand-held, especially with simpler sequences, like those used in landscape. You may notice that In cases involving extreme depth of field, you may notice the relative size of objects may change between individual exposures. These effects will be automatically adjusted during the merging process.

Before you combine a set of focus bracketed exposures, make all the Raw conversion adjustments you’d like to make to the final file. It’s quick and easy to process a focus bracketed series of files; process one file in the series ideally and then Sync the other files to it. Once a Raw file is rendered, you can’t re-access the data in it, such as ‘recovering’ highlights or ‘filling’ shadows, without re-rendering it. While, you can adjust lens distortions after stacking with Photoshop’s filter Lens Corrections, it’s much easier, faster and more robust to apply Lens Corrections during raw conversion, before focus stacking 16-bit TIFFs.

Once you have a processed set of focus bracketed exposures you can automate the process of stacking and blending them into a single file in Photoshop. (Unlike HDR and Panorama merges, you can’t make a focus stacked merge in Lightroom – currently.)

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Photoshop’s Auto-Blend Layers dialog

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Photoshop’s auto-masked layer stack

Take these four steps.

1          Using Adobe Bridge highlight all of the files you’d like to combine.

2          Go to Tools > Photoshop > Load Files Into Photoshop Layers

3          In Photoshop’s Layers palette highlight the layers

4          Go To Edit > Auto-Blend Layers, check Stack Images and click OK

You can then further refine these results, including manually adjusting the automated masks or distorting layers, but this is rarely necessary. Photoshop does a fine job for a majority of applications.

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8_HFmain

Helicon Focus’ main window

9_HFAutoadjustment

Helicon Focus’ Autoadjustment panel


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1_top

Top frame of a panoramic stitch

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Bottom frame of a panoramic stitch

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Panoramic stitch

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Panoramic stitch distorted

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Panoramic stitch cropped

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Panoramic stitch cropped and retouched

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Panoramic stitch retouched

The strategies above are not limited to panoramic stitches.

We’re responsible for everything that’s in the frame. We’re also responsible for everything that’s not in the frame. Deciding what’s in the frame and what’s out is a critical decision that can make or break an image.

Here are two essential framing strategies.

One. Use the frame to eliminate distracting information around a subject(s). Take extra care with image information that touches the frame, as it will draw extra attention. Do this with significant compositional elements.

Two. Eliminate excess space around a subject(s) to focus the attention of the viewer. A lot of surround space between the subject and the frame can be used to use to call on psychological associations with space, such as freedom or isolation. Some space between the subject and the frame can give the appearance of the subject resting gracefully within the frame. Touching the subject with the frame strongly focuses the attention of the viewer and may seem claustrophobic. Cropping the subject with the frame can focus the attention of the viewer on specific aspects of the subject and/or give an image a tense quality, evoking evasion and incompleteness – this often seems accidental if less than half the subject is revealed.

Cropping is extremely simple to practice. (While cropping techniques are simple to practice, the reasons for their application and the choices made about how to apply them as well as the final effects may be exceptionally complex.)

Here are two cropping choices.

One. Reposition the frame before exposure.

Two. Contract the position of one or more of the borders of an image after exposure, generally with software.

Because distorting an image during post-processing, by expanding or contracting one or more sides or corners, is a relatively new possibility, most people don't think of exercising this option. Ironically, anyone who uses lens profiles distorts their images in post-processing to correct lens distortion. Consider this a creative supplement to and extension of that practice. While cropping potentially changes the aspect ratio of an image, distortion does not.

Here are two distortion choices.

One. Use Photoshop's Edit > Transform to distort an image. Push the areas you wish to crop outside the frame. Move one or more sides by pulling the point in the middle.

Two. Use Photoshop's Edit > Transform to distort an image. Push the areas you wish to crop outside the frame. Move one or more corners by pulling the corner point while holding the Command key.

Retouching used to be complex. Today it can be simple. Never before, has retouching been so easy to do or the results so sophisticated. (To be certain, not all retouching is simple. You can make retouching as simple or as complex as you choose to make it. Retouching is an art that continues to be elevated on a daily basis. But what once required specialized tools and a Herculean effort can now be done with standard software in seconds.)

Here are four retouching choices.

One. There’s cloning. Simply use the Clone Stamp Tool set to Current and Below on a new blank layer. (This will ensure that any retouching can be removed or redone at a later date.) Hold the Option/Alt key and click to sample information to copy, then move the cursor to the area you’d like to copy the information to and click and drag. Repeat until a desired effect is achieved. Typically, donor information is drawn from the same document but you can also clone from one image or file to another.

Two. There’s healing. Use the Healing Brush Tool as you would the Clone Stamp tool. Or, use the Spot Healing Brush, which will automatically select the information sampled for you and can be used within a selection to contain the results. Or, finally the Patch Tool, which will copy information selected with it from or to (depending on whether you check Source or Destination) wherever you drag it to. Healing can’t be done on a transparent layer, so work on a copy of the layer you’d like to retouch. Click on the layer and select Duplicate Layer from the Layer menu or palette. If you need to heal image material contained on multiple layers, create a new composite layer by holding the Option/Alt key select Merge Visible from the Layer palette.

Three. There’s copying and pasting. Just select a region of an image with any selection tool. Copy it. (Edit: Copy) Paste it. (Edit: Paste) Then move the resulting layer into play and mask as needed. (Click the mask icon at the bottom of the layer palette and use a black brush at varying opacities to hide the information.)

Four. There’s filling. Select a region. Fill with Content Aware fill. (Edit: Fill and select Content Aware from the drop down menu in the dialog.) (This feature was introduced with Photoshop CS5.) Photoshop will automatically create an appropriate random texture in the selected area. Like healing, this feature won’t work on transparent layers/areas so, again, use it on a new merged layer.

Software routines such as lens correction and panoramic stitching may distort the frame, subtly but sometimes significantly distorting a composition, and requiring additional measures to restore a rectangular frame. When solving this challenge, you may get better results if you don’t contract the frame as aggressively as you once did and retouch rather than crop to fill in the gap and/or eliminate distracting elements.

Your choice of practices or their application may or may not change the nature of the artifact that you finally create. And, whether the means you choose is appropriate for your objective, the practices you adopt may or may not be accepted by the community of artists you choose to work within – some are more permissive than others. Nevertheless, you should explore your options. You simply won’t know whether it’s for you until you try it for yourself.

Learning to think within the frame is an essential skill for creating strong photographic compositions. But today, learning to think within the frame is only the beginning. You can learn to think outside the frame as well.

It’s a new mindset. Once it becomes second nature, you’ll not only find you have more options for visual problem solving but you’ll also find your visual horizons will have expanded – significantly.

Learn to see in new ways. Combine them with old ways. You’ll find you’ll make images that you once passed by, leaving them unmade or even unnoticed. As a result, you’ll make many more successful images.

Read more in my Exposure lessons.

Learn more in my digital photography and digital printing workshops.


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Reflection XXXVII

high noise / low noise

Noise happens. There is always some degree of noise present in any electronic device that receives or transmits a signal. Though noise is unavoidable, it can become so small relative to the signal that it is no longer visible. It’s all about a good signal to noise ration (SNR). The image is the signal. The capture and carrier mediums’ biproducts are the noise. (Film grain is noise.)The higher the SNR the more the image overpowers the noise; the lower the SNR the more the image becomes confused with noise. While some noise increases the apparent sharpness of images, the vast majority of noise found in images degrades quality. It’s best to avoid it.

There are a number of things you can do to reduce noise in your digital images at the point of capture.

1       Expose to the right

2       Use lower ISO settings

3       Use bigger sensors

4       Use faster exposure times

5       Keep equipment cool

Start here. Use software to reduce the appearance of noise only when needed. (Of course, reducing noise may not be the only deciding factor when selecting conditions, tools, and techniques. As with all things, you will have to balance many concerns simultaneously. Adhere to the above principles when practical.)

Knowing how noise is produced will help you avoid it.

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avoid the red zone, caution in the yellow zone, go for the green zone

ETTR

Underexposure results in more visible noise. Darker regions contain more noise than lighter regions in digital capture; the opposite is true of film. This is because the darker regions are recorded with fewer photons and less bits of data. It stands to reason that darker regions of images are produced with fewer photons. But why are they recorded with less bits of data? Digital cameras record data in a linear progression. If a digital sensor is capable of recording 14 bits of data (or 16,384 shades of gray) with a dynamic range of 8 stops, the lightest stop contains half the data in the file; the next lightest stop contains half as much data; and so on; it generates this progression from dark to light – 32 / 64 / 128 / 512 / 1024 / 2048 / 4096 / 8,192. This means you want to expose to the right. Avoid the lower 2 stops whenever possible; they contain less than 1% of the total data in the file. With so little data the signal becomes confused with the noise; the signal to noise ratio is very low. What’s more, when these tonal regions are adjusted, brighter or contrastier, the noise contained there quickly becomes more pronounced and with so few bits of data it also has a tendency to posterize. In addition, significant under exposure greatly increases the chances of producing Bayer pattern noise, a type of noise that is seen in larger areas and is more challenging to remove in post-processing. You’re much better off making a light exposure and darkening the Raw file during post-processing; this way your shadows will be represented with much more data and contain less noise. When light becomes challenging, which should you choose - under expose (without clipping) or raise the ISO? The precise cut off point is different for every camera, but in general avoid the lower 20% of the histogram. You’ll get less noise if you boost ISO and move the histogram up.

ISO

Higher ISOs amplify noise. ISO (International Standards Organization) is a descriptor that signifies absolute sensitivity to light. A digital sensor has one native ISO. Higher ISO settings simply boost the resulting signal. This is useful, but not ideal. When the brightness of the image is boosted, the noise is too.

Use “Shorter” Exposure Times

Longer exposures generate more noise. Hot pixels become hotter. All sensors have a few pixels that heat up faster than others, producing brighter than expected values. Some even have a few dead pixels that never fire, producing only black pixels. During longer exposures hot pixels are given more opportunity to heat up, growing brighter still; slightly hot pixels not visible at shorter exposure times become visible. As digital sensors age, hot pixels may become hotter and more pixels may become hot. Hot pixels produce a consistent fixed pattern of noise that can be recorded for given exposure times, making it easy to reduce. There is a duration at which a sensor suddenly produces a lot more noise; in older models this could be seen in exposures lasting only one minute, but with newer sensors this is greatly extended and most users will not encounter this; if you’re making very long exposures it’s useful test this and find the duration at which this happens for a your specific camera.

Use Bigger Sensor Sites

When it comes to noise, bigger is better – theoretically. Bigger sensors have more light gathering capacity, producing a higher signal to noise ratio, or cleaner images. More isn’t necessarily better. Cameras with more photosites (yielding more megapixels) packed into smaller areas tend to produce a lower signal to noise ratio, or noisier images. That said, a stronger signal does not necessarily guarantee lower noise. It’s the relative amounts of signal to noise that determines how noisy an image appears. The way a camera processes the file it makes has a significant impact on the final quality. Consequently, many medium format cameras that produce beautiful files in daylight typically produce noisier files than DSLR’s with smaller sensors in low light.

Stay Cool

High temperatures exacerbate noise. Thermal energy (leakage current) in semiconductors can generate an electrical signal that is difficult to distinguish from the optical signal. Ambient temperature increases leakage current by a factor of 2 for every 8 degrees Centigrade. Whether due to ambient temperature (You might start to see some effect over 90 F / 32 C degrees.) or storage (Don’t leave your camera in the sun, especially on a car seat, for long periods of time.), your camera can get hot and this will increase noise, which you can reduce by cooling off and keeping your camera cooler.

The best way to avoid noise is to produce as little of it as possible during exposure. These five tips will help you do just that.

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hdr_artifacts_425

Different HDR renderings accentuate different artifacts

HDR (high dynamic range) imaging captures extreme contrast ratios and subsequently renders them for LDR (low dynamic range) devices, monitors and / or prints. The very things that make HDR renderings appear natural can make them appear unnatural if taken too far.

Midtone compression

You can’t avoid midtone compression, they get caught in the middle when the relationships between highlights and shadows are compressed. But you can take steps to minimize it by being sensitive to this when choosing compression settings and amounts and by taking subsequent steps to expand it.

Tonal inversions

Some compression routines and settings can be so aggressive that they create inversions or solarizations of specific tonal relationships. Avoid this, there is no subsequent cure. If you like the overall effect of an aggressive setting and the inversion is contained to one area of an image you can render an image twice, once for the overall effect and once for a specific area, and then blend the two together using Photoshop’s layers and masks. 

Saturation Distortions

Saturation changes when lightness shifts but color stays the same. Because HDR produces effects that can be aggressive and localized to specific set of tones, the saturation shifts that accompany tonal compression often appear unnatural. Selectively adjusting the saturation of specific hues, with tools like the HSL panel in Lightroom or Camera Raw, can often convincingly cure a majority of these side effects and hide the rest.

Halos

HDR softwares help restore midtone contrast by accentuating contours. When used aggressively this edge contrast can produce halos.

Over the years, these algorithms have dramatically improved their ability to treat the halo (light line) separately from the line (dark line), suppressing the first more than the second. Sometimes, to avoid distracting halos at the border of skies, you may want to make a second rendering for the sky and blend it with another rendering using Photoshop’s layers.


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