I'm seeking recommendations for an Android app to view 2 images side-by-side (or one above the other) so that I can easily compare them.

Specifically, I want to compare quality of JPG image files to RAW (DNG) image files. I want to be able to load the JPG image on one side, and the RAW (DNG) image on the other side.

It's essential that I can zoom in on both sides. To make this easier, it would be great if the app could simultaneously zoom in on both images to the same level ("synchronized zooming").

Gratis apps are preferred, but I will consider apps of any price.

  • 2
    You do realize that any display of a "raw image" is but one of countless equally legitimate possible interpretations of the data in the raw image file? There's no such thing as "THE raw image" that can be displayed on any currently available screen. The only difference between a JPEG and one possible interpretation of a raw file is that the processing decisions have been irrevocably baked in to the JPEG. – Michael C Jun 6 '19 at 1:19
  • @MichaelC Thanks. I didn't realize that. My phone's camera can simultaneously create JPG and RAW files when taking a photo. When I look at the RAW files in the Gallery app, they get rendered, but appear a bit blurry. I think it's precisely because of the reasons you referenced. What I'd like to see is the JPG rendered next to a reasonable (might be hard to define) rendering of the RAW data so I can see the potential of the image (as compared to the compressed JPG). Does that make more sense? – RockPaperLz- Mask it or Casket Jun 6 '19 at 1:32
  • The JPEG has been rendered by the camera's processing engine from the same raw data recorded in the raw file. It's probably the most "reasonable" rendering you'll be able to auto-generate. The advantage of editing with all of the raw data is that a skilled editor can leverage the much greater amount of information contained in the raw file (but not displayed on your screen all at the same time) to optimize the conversion/rendering of the data to the specific conditions of the shot as well as the photographers intent for how they want the image to look. – Michael C Jun 6 '19 at 1:42
  • @MichaelC Thanks again. When I zoom in or enlarge the JPG images, they start to lose crispness. I'm hoping that by looking at an image generated with more of the RAW data, that crispness will be improved. Is that reasonable? – RockPaperLz- Mask it or Casket Jun 6 '19 at 1:47
  • Probably not. The biggest limitation of phone cameras are the small sensors and lenses. The computational photography and processing power applied to the jpeg engine by most smartphones capable of saving raw image files is already working pretty hard to maximize the quality of what is, relatively speaking, a poor quality raw file. The "mushiness" you see when you pixel peep is a result of the noise reduction applied. Small sensors with high pixel density can be quite noisy, thus more NR needs to be applied than with a typical larger sensor. – Michael C Jun 6 '19 at 1:56

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