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A tip on effectively enlarging a low resolution photograph

GaryGary -
edited March 2013 in Photography & Printmaking
Leana mentioned in one of her threads ( the difficulty of painting a portrait from a small, low resolution photograph. When she tried to zoom in all she got was a screen full of pixels and lousy resolution, obviously not helping her to get the detail she needed for the painting.

Many of us paint from photographs and have faced the same problem Leana mentioned. The obvious solution is to start with a high resolution photo but many times we get our photos from others or off the web and have no control over the resolution. We have to work with what we are given.

For those of us that use Photoshop I'm going to offer one solution that has helped me in effectively enlarging photographs. I'm sure Mark and David will be able to offer even better solutions in an up coming video but I thought I'd start a thread to offer my solution and hopefully get solutions others are using. If you have a solution, whether it involves Photoshop or another piece of software, please post it so we can learn how we might do a better job in solving this problem.

I found this solution on the web sometime ago but don't remember where exactly I got it but it works for me. At the bottom of this post I'm including some pictures that will help you see the difference.....kind of a before and after series of pictures.

Here's the procedure that I use:

1. Determine the size and resolution of your image. In the example (see below) the picture of fruit taken off the web and is 768 pixels by 1024 pixels (12.6 x 14.2 inches) = "original size".

2. Determine your desired size. In this example I determined I wanted the image to be 1080 pixels x 1440 pixels (15 x 20 inches) = "target size".

3. Enlarge your original image to size larger than your target size. I don't have a formula for this but I generally enlarge to something about 40-50 percent larger than the target size. In this case I enlarged the original size to 1512 x 2016 pixels (21 x 28 inches) = "enlarged size." In photoshop, use the "bicubic smoother" option to enlarge the photo. (Image/Image Size/Resample Image/Bicubic Smoother).

4. Next step is to diffuse the image using an anisotropic filter. (Filter/Styalize/Diffuse/Mode/Anisotropic)

5. Now reduce the size of your image from the enlarged size down to the target size.
(Image/Image Size/Resample Image/Bicubic Sharper)

6. Final step - sharpen you image. (Filter/Sharpen/Smart Sharpen)
Use these option setting:
"Advanced" button highlighted
"Settings" = Default
"Sharpen" Tab:
"Amount" = 150%
"Radius" = 1.3 pixels
"Remove" = Gaussian Blur
"More Accurate" = checked

Lets look at the results:
The first image below is the original, low resolution photo of fruit. To compare results I'm going to zoom in on one of the pomegranates.

The second image is a comparison with three pictures side by side (I turned the original image 90 degrees counterclockwise so the image would be horizontal on your computer screen). The image on the left is from the original picture.

The middle image is where I simply enlarged the photo from the original size to the target size using the 'usual' straight forward enlargement process: Image/Image Size/Resample Image/Bicubic Smoother. This is the same enlargement method mentioned above but not going through the "enlarged size", diffuse, sharpen steps outlined above. To me this middle image has about the same resolution quality of the original photo but we are getting a larger photo.

The image on the right is the result of using the anisotropic method outlined above. I see a better defined picture from which I could more effectively paint finer details of the pomegranate. I also get a larger image at my target size.

Hope you find this to be of some help. To repeat, if you have a process for effectively enlarging low resolution images please share them with us. Thanks!



  • [Deleted User][Deleted User] admin
    edited March 2013
    Gary said:

    I'm sure Mark and David will be able to offer even better solutions [on painting from low-resolution photographs]

    Don't. :P
  • This will be a huge help to me. Thanks!
  • A little behind on reading things but this is great info Gary, thanks
  • Gary has some good info to pass on for enlarging a low res photo. A method I have used requires the use of a scanner. With a good quality scanner, an image can be scanned at a higher pixel resolution and imported into photoshop. Say you would like to print the image at 300 ppi, and enlarge it 300%. By scanning it at 900 dpi, it can be enlarged by the 300% and still be at 300dpi. In otherwords, 900dpi divided by 3 {the enlargement multiplier} equals 300dpi. One caviat: the image to be enlarged must be of good quality or all of the faults, pixillation and poor color quality, will just be bigger!
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