Microsoft's WDP vs. Standard JPG, in Numbers

I heard you. Many users commented on my previous news post saying that they weren’t happy with the tests I performed. I understand where you were coming from, and I plan to address what I believe is probably the most important of the tests that were suggested. Now that an overview of the plug-in for WDP is out there, let’s verify Microsoft’s claim: “It compresses data twice as efficiently as JPEG, with either twice the quality at a given file size or half the file size at a given quality.”

My final test was performed by taking the two file formats in question and comparing which one can offer the smallest compression, without a major loss in quality. I saved the same file in both formats with lower and lower quality settings, until I hit visible artifacts. I then saved the file again a step up in quality (without artifacts) and compared to see if there were any obvious quality differences, while noting the file sizes. As I concluded in my previous article, WDP offers a much broader range of quality settings, and I wanted to see if this is why Microsoft claims that it can compress data twice as efficiently. Here are my findings for five images, two in black and white and three in colour:

  • A 1.0MB black and white TIFF image of a crouching man, at a resolution of 1024 x 1024
    • JPG: 75.6KB (Quality: 0/12)
    • WDP: 42.3KB (Quality: 0.3/1)
    At the lowest quality, JPG did not have artifacts, but it did get very fuzzy. With WDP just a bit over half of JPG’s file size, JPG was the clear winner in quality. The man’s face and hands were much more clear and crisp.
  • A 1.85MB colour TIF aerial image of the world, at a resolution of 2048 x 1024
    • JPG: 86.5KB (Quality: 0/12)
    • WDP: 83.1KB (Quality: 0.4/1)
    Even with 3KB of difference, I could distinctly notice that JPG retained the quality much better than WDP did. There was no point of comparing at half the file size.
  • A 12.9MB black and white TIF image of a boxer, at a resolution of 4096 x 3038
    • JPG: 209KB (Quality: 0/12)
    • WDP: 92.0KB (Quality: 0.4/1)
    Well below half of the JPG’s file size, the WDP file was very hard to tell a part from the JPG. There were differences, but they were so minor that I spent a good while making sure which one had a better quality. JPG did have better quality, but from what I could see, it was an immaterial difference.
  • A 10.3MB colour CR2 image of Dave Legg’s laptop taken by the man himself, at a resolution of 3888 x 2592, with a Canon EOS 400d 10.1MP camera.
    • JPG: 206KB (Quality: 0/12)
    • WDP: 115KB (Quality: 0.4/1)
    Almost half of the JPG’s file size, the WDP file was very hard to tell a part from the JPG. There were differences, but they were so minor that I could not decide which had the better quality.
  • A 13.4MB colour Olympus Raw File of a metal art plate, at a resolution of 3264 x 2448
    • JPG: 252KB (Quality: 0/12)
    • WDP: 169KB (Quality: 0.4/1)
    Not quite half of the JPG’s file size, the WDP file was very hard to tell a part from the JPG. There were differences, but they were so minor that I could not decide which had the better quality.
As we can see from the above, the bigger the image, the better WDP performs. When you want those really small images in order to save bandwidth, it looks as if you’ll need a pretty large starting image. This isn’t a problem with newer and newer digital cameras hitting the market, many of them supporting a RAW file format. Microsoft hopes to push this file format and the obvious place to start is with standardizing it for digital photography. Nevertheless, it needs to be able to perform better with other images, including those found on the Internet.

So, what happens when the two images are compared at the same compression percentage? Firstly, you will notice very little or no difference in quality. Will you notice a difference in size? Yes. Will it be half the size? Not always.

  • A 1.0MB black and white TIFF image of a crouching man, at a resolution of 1024 x 1024
    • JPG: 309KB at 75% (9/12)
    • WDP: 253KB at 75% (0.75/1)
    • JPG: 211KB at 50% (6/12)
    • WDP: 83.2KB at 50% (0.5/1)
    At 75%, there is no visible difference in quality but WDP is not half the size of JPG. At 50%, WDP is less than half the size, but a loss in quality can be perceived.
  • A 1.85MB colour TIF aerial image of the world, at a resolution of 2048 x 1024
    • JPG: 340KB at 75% (9/12)
    • WDP: 335KB at 75% (0.75/1)
    • JPG: 204KB at 50% (6/12)
    • WDP: 121KB at 50% (0.5/1)
    At 75%, there is no visible difference in quality but WDP is nowhere near half the size of JPG. At 50%, WDP is nearing half the size and a loss in quality can be perceived.
  • A 12.9MB black and white TIF image of a boxer, at a resolution of 4096 x 3038
    • JPG: 979KB at 75% (9/12)
    • WDP: 642KB at 75% (0.75/1)
    • JPG: 603KB at 50% (6/12)
    • WDP: 124KB at 50% (0.5/1)
    At 75%, there is no visible difference in quality but WDP is not half the size of JPG (at least a third less though). At 50%, WDP is one sixth of the size and no loss in quality can be perceived.
  • A 10.3MB colour CR2 image of Dave Legg’s laptop taken by the man himself, at a resolution of 3888 x 2592, with a Canon EOS 400d 10.1MP camera.
    • JPG: 1.06MB at 75% (9/12)
    • WDP: 766KB at 75% (0.75/1)
    • JPG: 558KB at 50% (6/12)
    • WDP: 160KB at 50% (0.5/1)
    At 75%, there is no visible difference in quality but WDP is not half the size of JPG (a quarter less though). At 50%, WDP is over a third of the size but no loss in quality can be perceived.
  • A 13.4MB colour Olympus Raw File of a metal art plate, at a resolution of 3264 x 2448
    • JPG: 959KB at 75% (9/12)
    • WDP: 528KB at 75% (0.75/1)
    • JPG: 581KB at 50% (6/12)
    • WDP: 221KB at 50% (0.5/1)
    At 75%, there is no visible difference in quality and WDP is almost half the size of JPG. At 50%, WDP is less than half the size and no loss in quality can be perceived.
In conclusion, WDP isn't always at 50% but often enough it is smaller than JPG with little loss to no loss in quality. Nonetheless, one must take into consideration that the higher the resolution, the harder it is for the human eye to detect discrepancies between images in different file formats. Therefore, since WDP offers a wider choice in settings, it is better at compressing larger images without major difference in quality, simply because the loss is inconspicuous at bigger sizes. That is what matters when it comes to digital photography, especially as cameras improve. Microsoft's new format will, however, have to perform better than JPG with smaller images, if it's going to make it. What really peaks my curiosity is the fact that this is a beta release. How much of an improvement (if any) will the final be from the beta?

Note: If you are wondering why there are no images that you can compare by yourself, it is because to get a true comparison, I would have to display both WDP and JPG. Browsers currently do not display WDP images. The links are there for you to do the tests yourself, or you can just take my word for it!

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