SharpeningCompared

Unsharpened / Hybrid / Strong HDR

HDR software is most typically used to render shadow and highlight detail, but it can also be used to enhance tonal separation and detail in any range of tones, even in images with extremely low contrast. The very same tools that are used to compensate for HDR side effects can be used to sharpen any image.

When multiple bracketed exposures are merged into a single processed file, shadows and highlights that exceed the dynamic range of a camera’s sensor are compressed into the dynamic range of a digital file, taking the mid tones with them. Depending on the HDR software used, a variety of tools are available to restore contrast and separation in mid tones. If used aggressively, these tools produce the telltale signs of contemporary or grunge HDR artifacts – halos and texture accentuation. These are the very same artifacts that digital sharpening routines use more conservatively to make images appear sharper - only they look different.

Unlike the hard halo and line produced by the filter Unsharp Mask and more like the soft line produced by the filter High Pass, HDR sliders can give you still more points of control over line and texture, each with a slightly different flavor.


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This issue features HDR techniques and celebrates women in photography.


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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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8 HDR Myths Debunked

December 12, 2016 | 2 Comments |

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There are many misconceptions surrounding the practice of high dynamic range (HDR) photography. Here are eight – debunked.

HDR is new

Within the first five years of the invention of photography photographers began bracketing exposure to extend the dynamic range of photography. They used chemistry to process their negatives instead of software to process their files – but they still bracketed exposures to capture contrast ratios that exceeded paper, glass, and film.

HDR is hard

High dynamic range imaging has become so commonplace that cameras and software make it increasingly easy to practice HDR techniques – auto-bracketing, merging and rendering.

HDR requires the use of a tripod

While there are times when the use of a tripod is required, when exposures are long in duration, in a majority of cases current cameras’ auto-bracketing features and softwares’ image alignment algorithms make hand-held exposure bracketing highly practical.


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back LCD menu

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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.


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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.

Read more on HDR techniques here.

Learn more in my digital photography and digital printing workshops.


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