What is the secret to taking a .jpg file that’s, say, 5" x 8" with a resolution of 90 ppi and enlarging it to roughly 36" x 48" with a resolution of 300ppi without having a huge file size and having it look good? The finished product is a banner printed on vinyl. Are there any tips you could offer?
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I use "Genuine Fractals" which is a Photoshop plug-in that regenerates the image, great for enlarging. Couple of things to keep in mind:
1.) It may be necessary to run another plug-in called "Image Doctor" by Alien Skin. Because you’re dealing with a .jpg file, Image Doctor can remove compression artifacts, as well as other fix-ups before you enlarge. You’re talking about approx. 600% enlargement, which means any image defects will be compounded 6x.
2.) Banners printed on vinyl are probably going to be printed via inkjet. If that’s the case, you only need 120 – 150ppi which will keep you file size lower than it would be at 300ppi at 100%.
Doesn’t 5×8" scale proportionately to 48×30"? And that is only at 12-15 ppi if you are starting at 90 ppi. Even if you use the tools John notes and allow the poster to be produced at 120 ppi, that is still an unholy stretch that will not look good. Hopefully, you are working with a picture of a blizzard.
The more sharply defined edges and the more detail in the original, the worse the enlargement will be. Even with the tools suggested, unless the original image is fairly soft and is bereft of fine detail, it will not look good on close examination. If the enlargement is not meant to be seen close up, so much the better.
But if you were to place your image and an original high-res version side by side after enlargement, in most cases you would see clear differences in quality, regardless of any electronic noodling you do.
Genie, the secret, is the Hollywood CSI filter plugin. It can do some pretty amazing things. But unless you know some TV or movie studio people its really hard to get one of these filters and they cost an arm and a leg.
