(06-30-2023, 03:50 PM)sedmont Wrote: Ofnuts, thank you for your reply.
I initially tried going to "Image" and clicking on "scale image" for one of the 300 x 300 ppi pages. I put 304 into the resolution boxes and put the exact page dimensions I needed into the width and height boxes. Then I clicked "scale" and got a warning that I would be creating a file that would take up almost twice the space on my hard drive that the original document was taking up. I clicked "scale" anyway, and gimp froze, and my computer almost froze. So I shut down gimp, and re opened Gimp to try a different method.
This should have worked. It looks like you put the "304" at the wrong spot or used the wrong unit and Gimp scaled the image 304x or something. If you image is X pixels wide at 300DPI, scaling it up for 304DPI is 1.3% increase, so a 2.6% file size increase... The size in pixels that you have in the dialog before you press enter shouldn't be much bigger than the initial size.
(06-30-2023, 03:50 PM)sedmont Wrote: The different method: I created a 304 x 304 ppi black background single layer document. Then I put all the layers from a 300 x 300 ppi page into a layer group and then and dropped the layer group onto the 304 x 304 ppi black background. Then when I saved the result, it only slightly increased the hard drive space used by the 300 x 300 ppi page. The layer group that I moved from a 300 x 300 ppi doc to a 304 x 304 ppi doc will have a slightly smaller size on the page, but not enough different to matter to me.
So you are just using the same pixels with a 304 DPI definition. This is the same as Image > Print size, that I mentioned above, just a lot slower to do.
(06-30-2023, 03:50 PM)sedmont Wrote: Why am I doing this? Because at 300 x 300 ppi, I cannot get the exact page dimensions I need (7.625 inches by 10.250 inches). I can only get 7.623 x 10.250 or alternatively 7.627 x 10.250. At 300 x 300 ppi, I cannot get 7.625 width. Seems to have to do with the size of a single pixel, which is evidently 4/1000 of an inch. So changing width of the page even by a single pixel causes page width to jump between 7.623 and 7.627. Can't get 7.625. But when I have a res of 304 x 304 ppi, I CAN get a page width of exactly 7.625. I guess that has to do with common denominators and common factors or something.
But I have to do this process 140 times (there are 140 pages to do), and each page tends to have multiple png and text layers, so I'm wondering if there is a quick way to get a bunch of layers simultaneously into a layer group, instead of having to put one layer at a time into the layer group.
Now, lets look at this calmly...
- You are worrying about an error of 2 thousands of an inch on a 7+ inches image. This is a 0.025% error... Have you ever wondered about the dimensional accuracy of your printer?
- To correct this you are either resizing the image (your first solution), which means interpolating pixels, which means adding other errors, or using a different definition which is (and I m quoting you here): "slightly smaller size on the page, but not enough different to matter to me.", so you are fixing the 0.025% error that seems very important to you by introducing a 1.33% error that you don't consider o be a problem...
By the way, this could be of interest: Image size in Gimp