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Experience "Camera Raw"

September 2013: Use this technique to process DSLR data the easy way.
RELATED TOPICS: ASTROIMAGING
tony_hallas
In my November 2012 column, I discussed a way to process your dithered RAW format DSLR images with Photoshop’s “Camera Raw” without having to apply the usual darks, flats, and biases. The theory behind this direct method of processing is that the tools in “Camera Raw” can extract every bit of data you capture.

Besides being able to stretch the data, you can address vignetting and noise reduction all in one stroke by using the right tools. Furthermore, it is possible to record your steps and apply this library of corrections to every one of your frames. That way, the processing tools will do all the work for you. You can conceivably process a huge number of exposures for maximum signal-to-noise ratio as long as you dither every one of the images.

Let’s assume you have thirty 2-minute exposures of subject matter taken in RAW file format. What you want to do is apply to all 30 the adjustments that you made to a “master” frame. Let me show you how by using Adobe Bridge CS6.

1. On the desktop, make a new folder and name it for the object you imaged. In my example, it will be “M42.” This is where your finished files will go.

2. In Bridge CS6, choose “Filmstrip” mode for viewing all your exposures.
Step-7-illustration
This screenshot illustrates step 7 in the text. It allows you to take the changes you made to one of your images and apply those steps to all of them. // All images: Tony Hallas
3. In Bridge CS6, find the folder that contains your 30 exposures and double click on it. The contents of the folder should appear as a filmstrip at the bottom of the page.

4. Find the first image, and click on it. Then hold down the shift key, scroll the filmstrip until you find the last image, and click on it. That should have selected all the images. Release the shift key.

5. Pick one of the selected images by right-clicking on it. From the menu, choose “Open in Camera Raw.”

6. Here’s where you can have some fun. Take all the controls in “Camera Raw” and make your image look as good as you can, including doing spot enhancements with the “Adjustment Brush.” You can apply myriad tools including curves, noise suppression, and color and detail enhancements, just to name a few.
Steps-8-and-9-illustration
Steps 8 and 9 are the subjects of this screenshot. Here's where you set the parameters for the images. In step 10, you will save all of them.
7. When you are done with your masterpiece, click “Select All” in the upper left corner, and then click “Synchronize.” A new window will open asking you which corrections you want to apply. If you used the “Adjustment Brush,” make sure you have that box checked. Once you click “OK,” “Camera Raw” will apply everything that you did to your initial image to every one of the images you selected.

8. Under the master frame, you will see some data. Click on it. Here you will set the color space, bit depth, size, and resolution of your saved image.

9. Once you have specified these parameters, click “Save Images” in the lower left corner. Here you will designate the file name, the destination folder (for me, it’s M42), and the file format.

10. When you click “OK,” “Camera Raw” will save every one of the enhanced images into your new folder.

In next month’s column, we’ll take these dithered images into RegiStar and have the software batch-process the tedious alignment procedure. Then we will combine subsets with a median/mean function to average the aligned images and remove outliers. We’ll then take the master frames from each subset and average them for a “grand master” 16-bit TIFF file.
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