> 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).
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).