I want to make a large poster (24 x 36 in) from an image in Photos. When I increase the pixel/in number of the image in Preview, the image increases but becomes more pixelated. The print shop says 300 dpi should do the job. How can I make the image, including text, clear enough so that it can be blown up to 24 x 36?
MacBook Pro 13″, macOS 10.13
Use the demo version of GraphicConverter (from the developer's site), crop the image to 3:2 and resize it to 36" x 24" at 300 pixels/in via the Resize menu.
In Photoshop, as I recall from last year, it was a matter of resampling the image 2 or 3 times. The poster came out beautifully.
I'm going to try the Image Enlarger app, otherwise I'm going to have to see how I can get a new version of Photoshop. Image Enlarger seems to have trouble uploading my photo. Wheel keeps spinning, saying "Processing, please wait." I have been waiting and waiting. . . Still waiting. The app lets me choose between "Zoom Factor" "Width" or "Height." If I try for each of the latter two, I get the interminable "Please wait." If I go for Zoom factor, it doesn't tell me what 2 or three means. If I use 3 or 4 for the Zoom, it tells me that I am over the limit, but does show images which are less, but still pixelated. I was hoping to create a poster as a birthday present.
I did a brief internet search for poster printing. I got lots of hits for services that make posters from photos. Places like Walmart, Staples, FedEx, and UPS do posters. And online services like Shutterfly, also do them. So, you might want to consider getting your photo posterized by an outside service, particularly if you are running up against a time constraint. Just a thought. I realize that you may wish to do it yourself, for a personal touch.
Or maybe you have a friend who has the newer version of Photoshop, and you can borrow his/her computer.
-- Rich
I've tried this a number of ways.
One jpeg is 2438h x 1728w at 72dpi
In Photo Image Editor PixelStyle, which I got from the App Store as an alternative to Photoshop,
I have a .psdb image that is 2514h x 1656w at 300dpi.
I had access to Photoshop two years ago when I did a similar poster and was able to resample and resample the image to get a much higher resolution.
Did you have the Resample Image box checked in the Preview Adjust Size box? I would like to know for my own purposes. Perhaps my eye is not attuned, but when I increased resolution from 72 to 300, with Resample Image checked, I couldn't tell on my computer screen whether there was a decrease in quality.
-- Rich
I'm expecting an increase in quality. If I am going to increase the image from 4"x6" up to 24"x36," I will need to have a much higher resolution. GraphicConverter 11 does not seem to be doing the job. Maybe that's because I don't understand the jargon. I'll try it again, but so far everything comes out pixelated even when the image size has gone up to almost 5GB in memory at 1200dpi. I haven't yet tried ImageEnlarger. I'm going to run disk first aid as I had to force quit GC11. It seems this should not be this difficult. Last year I did this in just a few steps using Photoshop which I can no longer access. Thanks to all three of you for responding and trying to help.
What are the pixel dimensions of the photo?
Quite a challenge. Best of luck with this.
— Rich
I am using the Online Image Enlarger to enlarge photos, without blurring the edges. This tool offers many different algorithms to add more pixels, and we can compare the results and pick the best version, see: http://www.imageenlarger.com/
I'm expecting an increase in quality
I think you're being optimistic. You're trying to increase the data in the image 6 fold.
One image is 2438h x 1728 that's a total of 4.2 megapixels/ That's not a lot of pixels. To get a poster that size at 300 dpi you'd be expecting 7+ megapixels as a minimum. So you're almost doubling the number of pixels. Then there's the issue of the quality of the original image. Perfectly exposed and sharp and detailed you might have some chance. If there are a lot of plain colours - for instance a large portion of the image is a blue sky, or a white wall - but if the shot is busy and detailed, and not especially well exposed, I fear your you're asking a lot of what ever app you choose to upscale the image.
Photo resolution
