Some good friends were planning a throwback, retro party. They asked for some help with posters and supplied this exact image of an old Burger King ad. But this image is small, as you see here. If you want a poster, what is the best way to enlarge small images?
So if you want this printed, you either take this 236px x 310px image to your local office supply store’s printing section and ask them to enlarge it up to poster size, with no control over their process. Or if you have the software tools available, you load it up in Photoshop and scale it to the size you need. But if you only do those two steps the software doesn’t do a very good job. The program interpolates the pixel data to enlarge small images in one leap. This causes it to make up information and stretch it over a far larger area. If you stand back it looks… OK, but not great. Upon closer inspection, you have gooey image detail.
Follow these steps to create believable, appealing textures that will give a more pleasing result when you enlarge small images.
Use this process to better enlarge small images:
I alluded to the solution above. The trick how to successfully enlarge small images is to not take the image to the full size in one single leap.
- If you can, try to find better a better source. (I don't want to get into copyright law here. That is a subject for a different post, having nothing to do with enlarging small images. This poster request was for a private party, a single-event and they weren't trying to sell hamburgers. We're moving forward, assuming you know if you're allowed to use your image legally.) Go to Google, select image search, drag the small image into the search field and search. There are search tools at the top where you can filter for medium or large files only. You should see similar images, by rolling over, you can see the image dimensions. Download any identical or close enough images that are larger and higher in quality. This is the most important first step to enlarge small images. When you get better source data, you have less to make up.
- Open up the image you decide to use in Photoshop or your image editing tool of choice.
- Take note of the current size and the final size you desire. If you want a print quality poster, remember 300 pixels per inch is the standard for high quality printing. For a poster, you may be able to get away with 150px/inch. Do the math and write down the future pixel dimensions you're working to reach. For my example, I wanted the BK poster to be enlarged to 24" wide, that's 7200 pixels. During my step 1, I did find a better source image. I was now starting from 660px x 878px. A lot better starting point!
- In your software, look for the resize tools. In Photoshop it is Image Size. Don't just enter 7200 where the 660 pixel with is! This is the key to this whole lesson. If you have a percentage increase, I recommend using that. Make sure your proportion is locked so that you only have to worry about changing one number. What we're going to do is bump up the size in small increments. Because I'm a bit of a nerd, I have a theory that being irregular mathematically helps the results a little more. We want to discourage the software from making changes that our eye will detect. Our eye can see artifacts (the garbled edges of items) and repeating patterns, (like a bad rubber stamp technique.) I suggest scaling up using prime numbers of percent increases. My favorites are 111%, 117% and 123%. Do your first scale by one of these numbers.
- Now repeat, but don't just pick the same scale over and over. Do one at 111, then a 123 and follow that with a 117. Hop around as the dimensions approach your final size desired.
- When you get close, slow down. I like to look around the image and judge if it needs some additional artificial detail. If it looks too smooth in places and you would like more grain or noise, copy the image and paste it above the current layer. Under Filters add some noise to this duplicated layer, adjusting the amount, (also uniform v. gaussian and monochrome settings) so that it looks most natural. Apply the filter. Now dial this upper, noisy layer back to about 50% transparent and save a new merged version.
- Take this merged layer the rest of the way up in one or two more steps to the final size you need. This file will likely be pretty large now, probably in the 15 - 25MB range. Save a new high-quality jpg of the image using 80-90% compression quality.
This new image will be much more successful for printing at a larger scale. You also won’t get software warnings, that your image is not large enough, if you upload it to a printing service.
The left shows the results of the process and the right is what one leap did.
>> Please let me know how it worked for you in the comments. If you have questions, please ask!