Double Save Confusion

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Today’s Question: When preparing a copy of an image in Photoshop for online sharing, after I save my JPEG and try to close the image, Photoshop asks if I want to save my changes. But I just saved the image! Why is Photoshop asking me about saving changes when I just saved my image?

Tim’s Quick Answer: The description makes it clear that the image in its current state is not supported by the JPEG image format. Therefore, Photoshop is asking you to save the image in order to preserve all features you have taken advantage of. If you don’t want to preserve those features, you could simply save the JPEG and then opt not to save the “second” time.

More Detail: There are a variety of features you can leverage in Photoshop that are not supported by a JPEG image file. For example, you can’t save a 16-bit per channel image as a JPEG. JPEG images also can’t include layers, saved selections, alpha channels, among certain other limitations.

If you have an image open that includes features not supported by the JPEG image format, you can generally still save the image as a JPGE. For example, let’s assume you are working with an image in the 16-bit per channel mode. You can still choose File > Save As from the menu and save the image as a JPEG, and that JPEG file will automatically be created in the 8-bit per channel mode.

But after saving that JPEG file, the image in Photoshop will still be the 16-bit per channel image you had been working with. Therefore, after saving a JPEG copy and closing the image in Photoshop, you’ll be prompted to save the image because at that point the full image (or the changes you’ve applied if the image had been previously saved) will not have been saved.

So, just because you’ve saved a JPEG copy of the image doesn’t mean you’ve saved all features of the image you’re working with. When that situation exists, Photoshop tries to make sure you’re not losing any unsaved changes based on the lack of support for certain features with JPEG images.