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Adobe Photoshop CS Review

Histogram Palette

The new Histogram Palette is a welcome (and overdue) addition. Previously, histograms were only accessible via the (now removed) Image -> Histogram command (which showed the luminosity and individual channel histograms) and the (still present) Levels command (showing the RGB and individual channel histograms). Having to look in two different places to view all the histograms was inconvenient enough. But the main drawback in earlier Photoshop versions was that the histograms were not updated as you changed the image. You could only see the effect on the histogram after you made the changes (e.g. Levels, Curves, Selective Color, etc.).

The Window -> Histogram command now brings up the new Histogram Palette, allowing you to perform your image adjustments while keeping an eye on the real time histogram and even view the histograms in the different channels simultaneously, allowing for much more precise adjustments and reducing the risk of clipping and posterization. The Histogram Palette shows a "ghosted" image of the "before" histogram, and updates the "after" histogram in real time.

Expanded view of the Histogram Palette showing the individual color channels
When making adjustments to the image, the original histogram is shown with reduced opacity

Extended 16 Bit Support

Working in 16 bit mode in earlier versions of Photoshop was possible but there were a lot of restrictions such as the inability to create layers, adjustment layers, selections, masks, etc. With some creativity and out of the box thinking, one could work around many of the issues. For instance, make a selection in an 8 bit mode copy of the 16 bit image and then import the selection via the Select -> Load Selection command. With Photoshop CS, this is now a thing of the past. The move to 16 bit mode was sensible, given the built-in RAW plug-in. This way all image transformations, including adjustment layers mode, can be performed without having to convert to 8 bit mode. With today’s fast processors and large hard drives, this is not a problem. Working in 16 bit mode is useful when editing images with subtle tonal gradations and/or where significant Curves or Levels adjustments are made, such as the Shadow/Highlight command which will be discussed below. It is also highly recommended when working in LAB mode as the "a" and "b" channel histograms are typically very narrow, so any adjustments have a higher risk of posterization (combed histograms). Working in LAB mode is useful for noise reduction as you can work on the color channels without affecting the detail which is stored in the lightness channel (for sharpening it works the other way round).

Color Match

The new Image -> Adjustments -> Color Match command allows you to adjust the color balance based on a complete or partially selected other layer or image. For instance, the animation below shows how I applied the correct color balance of the first image to the second image. The first image was blur and not correctly framed but had the correct color balance while the second image was sharp and correctly framed but had the wrong color balance. So I selected the first image as source in the Color Match dialog box and then made minor adjustments via the Luminance and Color Intensity sliders. It is a great feature to streamline images for montages and panoramas.

Color Match dialog box

Shadow/Highlight Command

Many third party packages, actions, and plug-ins are available, but just like "Auto Levels" works well in many cases, they will never give an optimal result for all your images and they often take away your creative control. Often they cause posterization, and as shown in the example below, "halos" around the edges. The edges are always the problem areas and will reveal how good a job was done. The new Photoshop CS Shadow/Highlight command offers the perfect balance between automation and tunability.

Shadow/Highlight dialog box

This new command reduces bringing out shadow detail to one single step. Of all the actions and software I tried, this command is the best I have seen so far. It matches manual methods and does it in a fraction of the time. I applied it on an image that I used for the Nikon Coolpix 5000 review on this website. This image, which was difficult to adjust, was fixed in just a few seconds using the standard sliders. Instead of selecting the areas to be adjusted with layer masks, the dark and bright tonal ranges can now be selected via "Tonal Width" sliders. Levels and Curves adjustments are replaced by "Amount" sliders and the effect of brush radiuses and gradients is replaced by "Radius" sliders. The result is a highly tunable dialog box that creates equivalent results as the manual method but much faster and better than many other automated methods. Even more powerful when keeping an eye on the above mentioned Histogram Palette, allowing you to see the impact of your changes. Combine that with the ability to do all this in 16 bits/channel mode and you are able to extract virtually all possible shadow and highlight detail in the image. Of course combining bracketed images will still lead to superior results, as shown below, but it is also an order of magnitude more difficult to perfectly blend bracketed images, and they may not always be available.

Original -1.0 EV image

Example of "halos" resulting
from poor automation applied to the -1.0 EV image

Photoshop CS Shadow/Highlight command applied to the -1.0 EV image

-1.0 EV image adjusted manually
Combination of the -2.0,-1.0, 0, +1.0 EV bracketed images
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