Today’s Question: I hope you can help with a frustrating issue. I open a JPEG in Photoshop, crop the image, and when I go to Save (not Save As) Photoshop insists on Save As and wants me to save the image as a Photoshop PSD. Why can’t I just re-save to update the JPEG I opened?
Tim’s Quick Answer: In this case it sounds like the “Delete Cropped Pixels” checkbox is turned off for the Crop tool, causing the Background layer to be converted. If you choose Layer > Flatten Image before saving, you should be able to save the image without the Save As dialog appearing.
More Detail: Photoshop will default to the Save As dialog with the file format set to Photoshop PSD when any of the attributes of the image file are no longer supported by the existing file format.
For example, the JPEG format does not support bit depths above 8-bit per channel, layers, or saved selections or alpha channels. In this particular case, since the image is being cropped, it sounds like the “Delete Cropped Pixels” checkbox is turned off. Therefore, the Background image layer is being converted to a normal layer, so that the cropped pixels can be hidden outside the boundary of the canvas, rather than removed from the image altogether.
Flattening the image with the Layer > Flatten Image command will cause the image layer to be converted to a Background image layer (and cause the cropped pixels to be deleted in this case). That will once again enable you to simply use the Save command without seeing the Save As dialog.
In general, the solution here is to make sure the image attributes support the current file format.