how to change the resolution of a picture on mac

This will give 300 dpi but anything smaller than A3 and I’d aim for a higher resolution. Using this we come up with the following sizes for printing a poster. Or multiple the mm by 300 but divide by 25.4 as well. So to get DPI you can multiply the inches by 300. To go from mm to inches you divide by 25.4 Size GuideĪs a rough guide (for 300 dpi print – the minimum)Īn A1 page is 594 x 841mm or 23.4 x 33.1 inches. This should blow up OK to an A0 size or large banner. You can also see that the dimensions are roughly 12,000 x 17,000 pixels. That’s quite reasonable for a large image and it is still small enough to email. Here you can see that the file size is 8.5 MB. Here you can see the file size and the final output size. It’s a bit of trial and error but you can export the file and see what the exported file looks like then go back and do the process again with a larger or smaller number.Ĭlick on the file you ave exported and then select ‘Get info’ from the File menu. So the original file needs to be 3000 dpi for the final one to be 300 dpi if you want to make it 10 times bigger. If you take a 300 dpi image and make it 10 times larger then the output will be 30 dpi and look very dotty. The file will not really be 3000 dpi, because I am blowing it up. The lowest resolution you want for printing is 300 dpi.

Open the pdf file with the free ‘Preview’ app built in to Mac OS. But our printing shop wanted it as an image file not a PDF. If it was a PNG file I would not be able to blow it up but because it is a PDF file with the font in built it means I can make it as large as I can and it still looks good. It was a postcard designed by a graphic designer for our Christmas meetings. This postcard was designed by Virtual Church Assist

How to change the resolution of a picture on mac