I have a question regarding image DPI. I have a screen capture image JPEG at 300 DPI but when I load it and save it in ImageJ it changes to 96 DPI by default. Is there a way to control this ? The JPEG image quality is set to 100%
welcome to the forum!
I am not entirely sure, that I have understood your problem. The 300dpi JPEG you are talking about has a size of X pixels * Y pixels which the re-saved version should also have. I’d be worried if opening and saving that image would change its size.
That said, the DPI should be irrelevant to ImageJ as they are only relevant with respect to printing the image afterwards. My guess is, that ImageJ writes the 96dpi per default because dpi is required information for JPEG? You should therefore be able to change the DPI back to 300 when printing the image.
Does this make sense?
Quite incredibly some journals insist that you submit images at a given DPI value without realising that for some images this does not make any sense, e.g. when they are synthetic and not scanned, and furthermore we do not know how large the images are going to be printed (!).
A couple of times I tried to argue this with the editorial office, because insisting on the DPI makes no sense at all when you do not know the final image size. Eventually I gave up and now I load them in GIMP and just set the DPI value they want and save it again. No more editorial complaints…
That makes me a little sad (not the fact that you gave up but that fact that you were “forced” to give up…)
Not forced, I had the chance (but not the will) to carry on the argument. The problem is that in that case, dealing with the editorial office, you are not arguing with somebody who really understands the problem and is likely to change the policy of the journal and accept the images “as they are”.
Most likely they were told by the typesetter that a minimum of nnn DPI is what they aim, so unless the tiff image has that magic number telling them it is correct, they will ask you to “rescale” it.
Understand that it does not have much significance. Just that it would help if ImageJ could just keep the value rather than set a new default value.