Tech-Hack!!

Introduction

Photoshop CS is no doubt the most significant Photoshop move towards digital photographers. Although this upgrade also provides exciting new features for general users, web designers, and even video editors, this article will focus on some of the exciting new features most useful to digital photographers.

The simplicity of the Photoshop CS interface is as deceiving as its predecessors and at first it appears as if little has changed, making the transition from Photoshop 7 to Photoshop CS very natural, preserving most of your Photoshop learning curve. However, a closer look reveals a large number of exciting new features ranging from major things such as RAW support, and the Histogram Palette to minor things such as Crop and Straighten and the Bicubic Smoother and Bicubic Sharper interpolation options.

Camera RAW

The RAW part of the separate Photoshop 7 Adobe Photoshop Camera RAW & JPEG 2000 Plug-in Bundle which was sold separately is now an integrated part of Photoshop CS and has become substantially more powerful. JPEG 2000 delivers superior quality for the same compression ratio (or superior compression ratios for the same quality). However, since no cameras currently support JPEG 2000, support for this format is available through a separate plug-in that ships with the software.

Camera RAW - White Balance and Exposure

Unlike the more universal JPEG format, RAW comes in many flavors, depending on the camera brand. It is usually processed by software provided by the manufacturer or specialized third party software. Adobe Photoshop CS covers most RAW formats available today. However, given the proprietary nature of the various RAW formats, the RAW data may not always be read 100% correctly. For instance, the white balance of Nikon Coolpix 5000 images turned out unnatural, which was not the case using Nikon's own Nikon Capture 3.5. That being said, it was relatively easy to fix the white balance by clicking in a non-specular white area, followed by a minor tint adjustment. Further adjustments can be made via the advanced "Calibration" tab. Moreover, you can save your settings and use these as a start for subsequent images from the same camera so you will not have to make these adjustments every time.

Before white balance and exposure adjustments	After white balance and exposure adjustments

The "Adjust" tab of the RAW dialog box has also exposure, shadow, brightness, and contrast sliders. Although these have of course a similar effect as Levels, a per channel Levels adjustment feature would be desirable. Also missing is a (per channel) Curves adjustment, present in higher end RAW software. The "Adjust" tab has also a main saturation slider, while the advanced "Calibration" tab allows you to fine tune the hue and saturation of the individual color channels, as well as the shadow tint. Even though Photoshop CS features now a new Histogram Palette, the RAW dialog box also features live histograms.

Camera RAW - Noise Reduction

Analyzing and developing noise reduction methods is one of my favorite digital imaging activities. With Photoshop CS, Adobe has created an excellent noise reduction method for RAW files via the "Detail" tab. It would be great to have this feature implemented for JPEGs as well.

Before noise reduction	After noise reduction

The color noise reduction and luminance smoothing sliders allow you to reduce color and luminance noise independently. The latter should be used with caution because it can quickly lead to an artificial "water paint" effect with too uniform surfaces. Overall, the noise reduction performs very well and preserves image detail and edge sharpness. However, there is still room for improvement on large uniform areas as shown in this example which just focuses on the red channel where the noise is most visible. The wavy pattern in the sky is typical for automated noise removal methods, and is the result of blurring the LAB color channels, thereby smoothening color noise while leaving the lightness/luminance channel (and hence sharpness) intact. Manual noise removal can lead to much more uniform skies but requires more time, the typical digital imaging trade-off.

RGB composite image after noise reduction	Red channel before noise reduction	Red channel after Photoshop CS RAW noise reduction	Red channel after manual noise reduction

I also noticed that when this particular Nikon *.NEF image was opened in Photoshop CS without noise reduction, the noise was stronger (albeit more looking like real film grain) than the typical noise present when opening the same file with Nikon Capture 3.5, indicating the RAW data are processed differently in both programs.

Camera RAW - Chromatic Aberrations

Chromatic aberrations are typically removed by applying a local desaturation in the corresponding color channels. The "Lens" tab of the RAW dialog box provides a very easy to use and effective way of reducing certain types of chromatic aberration as shown in this example. I look forward to having this feature implemented for JPEGs as well.

Before chromatic aberration removal	After chromatic aberration removal

There are also two sliders to reduce (symmetrical) vignetting.