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.
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.
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.
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.
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.
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.