Ignoring the fact that the original image [1] had banding issues (e.g. top left), and ignoring the fact that JPEG is a format which optimizes file size by taking advantage of the limitations of the human eye as well as typical properties of REAL photographs (ie NOT cartoons, and NOT images with largely the same tone {'orangy' in this case}), I think you have to agree that my result from the standalone JPEGMini app [3], is markedly better than your "lossy" example [2]
Your lossy sample is brighter, has major artifacts around pointy hair bits, the sickle, etc. and in zoomed in mode, which is not how you should compare these things, there's a distinct lack of detail.
If you were to repeat the same comparison with a realistic photo, the differences between the original and the jpegmini version, there are some, but you have to look hard, would be even less noticeable.
Please note: JPEGMini does not allow me to set any parameters at all.
In short: a single drag/drop on my part reduced a file from 1.8MB to 410kB and differences are extremely minimal. Another win for jpegmini.
I used the exact same application as you did. JPEGmini lite from the App Store. I'm not sure what could account for the discrepancies between our examples. As you mentioned, there's no possible parameters either of us could have changed.
> and in zoomed in mode, which is not how you should compare these things
I see no issue with zooming to demonstrate already visible compression artefacts.
> ie NOT cartoons, and NOT images with largely the same tone
JPEG compression actually looks better on images with flat areas of color of gradient. This can be demonstrated by exporting an image in the format with and without a very slight gaussian blur added to the image. The results are typically a good deal smaller with the blur applied.
> I used the exact same application as you did. JPEGmini lite from the App Store. I'm not sure what could account for the discrepancies between our examples. As you mentioned, there's no possible parameters either of us could have changed.
I used the non-lite version (ie I paid for it). Version 1.4.2 to be exact (I see the latest version is 1.4.3). Not sure if the "full" and "lite" version are using different compression levels or algorithms. I do know that older versions had a much lower megapixel limit.
> I see no issue with zooming to demonstrate already visible compression artefacts.
I do, because that's the crux of the story. JPEGMini (and Beamr too I guess), provide VISUALLY similar results with smaller file size and with a minimum of effort required.
Loss of information is inherent to lossy compression. Achieving a file size reduction requires that sacrifices are made somewhere, typically by removing detail. The trick is making these sacrifices in the right places, so that before and after appear the same.
If the processed image is displayed at 800x600 on a monitor with 150DPI, one would make different choices/assumptions about what to sacrifice than if the resulting image is viewed at 300% magnification. JPEGMini's feat is making the right sacrifices (note that they do NOT change the compression method, the end result is a STANDARD jpeg file, not a special format).
> JPEG compression actually looks better on images with flat areas of color of gradient. This can be demonstrated by exporting an image in the format with and without a very slight gaussian blur added to the image. The results are typically a good deal smaller with the blur applied.
Correct, but photos are still very different from cartoons, vector graphics, text, etc (think: colors occurring in nature vs colors picked by a designer, inherent blurriness of large parts of a photo, very few hard edges in most photos, the human visual model - color, luminance vs chrominance, filling in the gaps etc etc).
That image has too much noise. You need smooth gradients to get banding. The pony, the smoothest part of the image, has a lot of sensor noise (more chroma than luma but still) in the 3-6 pixel frequency range.
I was trying to prove my photo point ("If you were to repeat the same comparison with a realistic photo, the differences between the original and the jpegmini version, there are some, but you have to look hard, would be even less noticeable.")
There's certainly less impact on that image. The lower left section looks awfully blocky, but that's somewhat to be expected given the size of the image. The main difference in all of these examples is the loss of CCD noise, which could be considered a good or bad thing depending on your aim.
[1] https://dl.dropbox.com/u/139377/ThreePonies/00-ORIGINAL.jpg (1.8MB)
[2] https://dl.dropbox.com/u/139377/ThreePonies/01-YOUR-LOSSY.jp... (121kB)
[3] https://dl.dropbox.com/u/139377/ThreePonies/02-MY-LOSSY%28JP... (410kB)
Your lossy sample is brighter, has major artifacts around pointy hair bits, the sickle, etc. and in zoomed in mode, which is not how you should compare these things, there's a distinct lack of detail.
If you were to repeat the same comparison with a realistic photo, the differences between the original and the jpegmini version, there are some, but you have to look hard, would be even less noticeable.
Please note: JPEGMini does not allow me to set any parameters at all.
In short: a single drag/drop on my part reduced a file from 1.8MB to 410kB and differences are extremely minimal. Another win for jpegmini.