[JC]

research need
  • Our software often relied on loading from remote servers that used wireless cell networking in rural areas.

  • This often led to slow loading times for our customers. We needed a way to reduce file size without sacrificing image quality for our UIs.

strategy
  • The first blush "obvious" answer is to just compress the images into a lower quality jpg, but my research showed different results.

research
  • I decided to my own testing and document the results.

  • I created my own experiment to determine what the best method would be.

experiment and methods
  • Each image began as a reference PNG file. Each file was then saved or converted in a variety of ways using different compression algorithms either in JPG or PNG format. The files were then each compared to the original reference PNG file to check for changes in image quality.

  • The same tests were run on each image, and then evaluated subjectively for image quality. The new file size, percentage of file size change, and the effects on quality are reported in the table under the compression method used.

  • The optimal setting for the tested images highlighted with a yellow box. The resolution for the original image, and compressed images, is listed below the image thumbnail.

result
  • I found that a JPG is not always the correct choice, and that different compression methods and file types play a significant role in image quality.

  • The content of the image highly affected the results of each method used for saving.

  • Based on my findings, I recommended the following strategies to our SCADA techs: