After a recent shoot I experience a lot of problems uploading to various social media sites. In this era of mobile devices many of these sites are aggressively compressing images in an effort to streamline bandwidth. By now you’re thinking exactly what I’ve been all along… “Why don’t they use hardware to handle the bandwidth?”
…The simple answer? Money…
Here’s a quick “How To:” for minimizing or preventing the problems all together associated with aggressive compression. If you want to know how it works I’ve also included some background info. at the end of the post.
1. Open Hi Res Image Tiff (300dpi minimum)
2. Flatten Image
3. Select File>Save for Web>
4. Select PNG-24 (PNG Lossless Compression with 24-bit (large color depth)
5. Check off Interlaced
6. Convert to sRGB
7. Select Preview: Use Document Profile: Doesn’t do anything to the image rendering but it’s nice to see what your image will look like.
8. Specify Image Size: 2048x2048 max or 2048px longest edge (Facebook’s maximum allowed image size dimensions for album photos)
9. Select Quality: Bicubic
Now I can get into the technical details but let’s face the facts. We just want to be able to upload quality images but a little bit of information goes a long way so here are the basics to why this way works.
Converting hi-res images to low-res(72dpi) jpgs is the standard method of preparing files for the internet. That’s worked till now but sites are adding even more compression to images that have already been compress when we create jpegs. As you all know adding compression to an already compress image is one of the worse things to do if you want to retain image quality. PNG however employs “lossless compression." Lossless compression allows the exact original data in the image to be reconstructed in it's original form. Since social media sites add compression to the images during the upload process, by using PNG we can prep our files for the internet yet minimize the loss of quality through compression. But this is only part of the story. Because the compression that is being employed is becoming increasingly aggressive this alone is not enough. Here is the important step…
Using 24bit PNG (PNG-24) instead of 8-bit PNG increase the information that is available for images and choosing Bicubic interpolation we will have the best results with transitions between colors such as in gradients skies.
Well… there you have it! Happy posting!
Interesting Links:
Social Media Images Size Requirements/Guidelines:
PNG history:
http://en.wikipedia.org/wiki/Portable_Network_Graphics
Bicubic vs Bilinear, Bicubic Smoother or Sharper
http://www.earthboundlight.com/phototips/bicubic-smoother-vs-bicubic-sharper.html
Kemachat Photography