Today’s Question: When editing JPEGs that I used in my early days of digital photography I’ve always opened them in Photoshop and used “Save As” to get a TIFF file and then edited from there. Is that not a good option?
Tim’s Quick Answer: Saving a JPEG image as a TIFF file before editing is a good approach, as it ensures you won’t create additional degradation of the image by saving multiple times with JPEG compression.
More Detail: JPEG images exhibit visible artifacts based on the way JPEG compression works. This can lead to a somewhat obvious grid pattern in the image, which can be distracting. The pattern is often quite difficult to see, but once you notice it you may find it difficult to ignore.
If an image was captured or saved as a JPEG, there will always be a degree of artifacts from the JPEG compression that you really can’t do anything about. In other words, saving a JPEG file as a TIFF won’t remove the JPEG artifacts, it will simply prevent them from getting worse.
Each time you make changes to a JPEG image and save it again, the JPEG compression algorithm processes the image data, which can lead to further degradation of image quality. It is therefore best to avoid saving updates to a JPEG image when applying adjustments, in the interest of maintaining maximum image quality.
Saving the JPEG as a TIFF image either without compression or with a lossless compression option (such as ZIP or LZW) will ensure that additional image degradation will not occur from compression, since no additional lossy compression is being applied after that point.
Of course, as a result of saving the image as a TIFF file the file size will be significantly larger. For example, a JPEG image that might be less than two megabytes in size might translate to a TIFF image of around twenty megabytes. In other words, you’ll be consuming quite a bit more storage space when saving a TIFF based on a JPEG image. This is certainly something to consider, especially since the reality is that if you use a high setting for the Quality option when saving an updated JPEG file, the degradation in image quality is quite minor.
