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Digital Workflow - Part 2 - Adobe Camera Raw
In last weeks tutorial I have shown you how to use Adobe Bridge. Today we will check out how to process RAW files with Adobe Camera RAW. This is the second step in processing your images. If you are only dealing with JPG images, you may skip this tutorial. If your camera has the option to record raw images, I highly recommend using them. You can always just batch process them later into JPG if you fear that you will not have enough time for advanced image processing, but you still have the option to process one or two images manually and get much more bang for your buck. Think about it this way, storage is cheap, but going back to a place since you didn't get that shot right is expensive. I have reviewed Image Tanks which is also a good option for longer vacations, to store all those digital RAW files without having to bring along a computer. If you still have doubts, read this tutorial or some of the mentioned benefits of RAW photography on last weeks tutorial.
This tutorial will deal with Adobe Camera RAW (ACR) version 3.0 that ships with Adobe Photoshop CS2. Most of the functionality is also available in earlier versions of the software that came with Photoshop CS or was available as a plugin for PS 7.
Assuming you have Adobe Bridge already open, simply select the image you want to process and right click on it. The context menu (see picture) will open, where you can choose "Open in Camera Raw...". You can also select multiple images in ACR, which will be very useful for equalizing white balance across multiple images (especially helpful in stitching panoramic images). Right now we will open up the image of Portland with Mount Hood in the Background.
When we open Adobe Camera Raw we will see something like this. At first it may look a bit confusing, but the user interface is actually designed with a lot of thought. I have picked a somewhat difficult image to show some of the fine tuning that can be achieved with ACR.
The color histogram gives you an overview of the distribution of the three basic colors (Red, Green and Blue) as well as the combination of the three (white). On the left side are the dark colors (shadows) and on the right side are the bright colors (highlights). When you take a photo, you will want to avoid hitting the very right side, since this means clipping can occur (that means information is lost). It is important to keep an eye on the histogram while doing adjustments.
Lets check out the Color and Resolution Tab.
When you click on the selector for "Size" you will see a resolution menu unfold. Per default the native resolution of your camera should be selected (here 8.2MP for a Canon 20D). Resolutions (actually size here) above the native resolution are marked with a "+" sign and smaller resolutions with a "-" sign. Unless you have a reason to change this, don't touch it. There is a way to use this to increase the resoltion of your output images, but it has to be used with care and proper post processing (sharpening, detail extraction ...). This will be part of another tutorial. For now don't change it.
Changin the "Resolution" settings will not have an impact on your image size (number of pixels). You can always change this later in Photoshop without loosing data.
Depth: This defines the number of colors that will be extracted per channel (RGB). As I mentioned in last weeks tutorial, the Canon Cameras record 12-bit color data per channel. Since most image formats only support 8-bit or 16-bit we are going to select 16-bit here. Otherwise we would loose information and thats bad for editing.
During the editing process we might decide to use curves, brighten shadows ... . Lets say we had an 8-bit image and we would brighten it to be twice as bright. This means all color values are shifted to the brighter levels resulting in the brightest colors being clipped and leaving your with a 7-bit image. Had we chosen 16-bit to begin with we whould have a 15-bit image (no big deal as our final result will be a 8-bit JPG).
Space: This is the color space of your image. The final image (for printing) should always be sRGB, but at this moment we are choosing ProPhoto RGB. Having this option is really phantastic. Basically ProPhoto RGB has the widest Gamut range of all color spaces. Next in Line is Adobe RGB and then sRGB. We are choosing ProPhoto RGB for a similar reasoning as we do on the Depth. We want the maximum range for editing and we will convert the image at the end of the process. I guess you can believe me at this point or try out for yourself. If you choose ProPhoto RGB and increase color saturation of your image and then convert it back to sRGB you will not get any out of Gamut images as you would otherwise (more about this in one of the next tutorials).
The "Adjustments" section is the most important part of all. Here is where you adjust your image properties. There are so many options here, that I decided to make the next Workflow tutorial all about this. As I mentioned earlier I have chosen a difficult image to show some of the more elaborate tweaks you can perform. With a basic curve adjustment I am going to extract much more detail from the mountain that was hidden in haze:
Compare this to an image converted without any adjustments:
When you click on the options tab (the little circled arrow), you will see this menu. One of the most important things to turn off is "Use Auto Adjustments". Once you have done that, you should open this menu again and click on "Save New Camera Raw Defaults". Although the Auto Adjustments work pretty well for most cases, they are also applied in Adobe Bridge. Suppose you took an exposure bracketed shot of a scene (several different exposure values). You are expecting to see a dark, a normal and a light image in Bridge. However they will all be adjusted to look the same if Auto Adjustments are left on. So how do you decide which shot is the best (the one with the histogramm to the right but not hitting the right) if all are adjusted the same. While the dark image will be brightened (and thus get noisy in the shadows), the bright image will get darkened (and still have less highlights for processing).
The tools consist of a magnifying tool, hand tool (for panning), a white balance tool, color selector, crop tool, straighten and two rotate buttons (which I never use since the 20D always determines the correct rotation). All of these tools are quite intuitive. If you have an area in your picture that is a shade of white (grey), you can use the white balance tool and click on that area. ACR will then automatically determine the correct white balance. I rarely use this, since it really doesn't account for different lighting conditions (sunset vs. mid day, filter vs. no filter). The straighten tool is also very simple. If you have a horizion thats slightly slanted, just select the tool and click on one end of the horizion. Then drag it across to the other end. Camera Raw will automatically determine the correct rotation of your image and adjust it.
It is my belief that you should rotate images during the RAW conversion and not in Photoshop. This is due to the bicubic interpolation that is being used when you rotate an image. Since the RAW conversion also involves anti-aliasing (for color interpolation), the image needs sharpening anyways. Once the image has been sharpened (by the RAW converter), I try not to perform any unnecessary interpolation in Photoshop.
In the next Tutorial we are really going to dive into the RAW conversion and how to adjust images and then we will spend a few pages (or more) on Photoshop fine tuning.