Ask Tim Grey - JPEG in Camera Raw

Ask Tim Grey eNewsletter, March 29, 2010, Learn more at http://www.timgrey.com/

Today's Question:
Are there any benefits opening and adjusting JPEG files in Adobe Camara Raw over Photoshop adjustments, since JPEG files are in a way already compressed image files that don´t have the advantages of RAW files?

Tim's Answer:
The benefits of opening JPEG images with Adobe Camera Raw relate primarily to workflow and convenience rather than image quality. You're absolutely right that the primary benefits of converting a RAW capture through Adobe Camera Raw (or any other RAW conversion software) relate in large part to the fact that the RAW capture contains high-bit data that has not yet been full translated in terms of actual RGB pixel values. With JPEG images, not only has compression been applied, but the RGB values have been determined and the information is in 8-bit per channel mode. Thus, most of the benefits you could gain through RAW conversion will not apply to JPEG images processed with Adobe Camera Raw.

While you really won't gain anything in terms of image quality when it comes to opening JPEG (or TIFF, for that matter) images with Adobe Camera Raw, there are some potential benefits. For example, the White Balance adjustments (which are actually based on the color balance adjustments you'll find in the Lab color mode) can sometimes be easier to work with than the traditional color balance controls you'll work with in RGB mode. Another good example relates to image cleanup. While I generally prefer to perform image cleanup work on a separate layer within Photoshop, Adobe Camera Raw does provide the benefit of being able to apply the same cleanup to multiple images. So, for example, if you have captured a series of images that exhibit spots caused by dust on the imaging sensor, chances are the exact same adjustments that will work for cleaning up one of the images will work well for all of the images in the series.
So, there are some potential workflow advantages to opening JPEG and TIFF images (especially multiple images) in Adobe Camera Raw, but these benefits only relate to workflow issues and do not relate to image quality.

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