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Well, yes. But I think the whole point of this technology is that you don't have to come up with the 85% number. It can be a lot of work to find the lowest qua

Well, yes. But I think the whole point of this technology is that you don't have to come up with the 85% number. It can be a lot of work to find the lowest quality setting that will be perceived as (near) lossless. Think millions of files.

mistercow 14y ago
I see now that this is what they purport to do. However I still maintain that the presentation is dishonest. Showing a comparison at 25% scale gives the impression that the tool is better at choosing "nearly lossless" setting than it really is. Look at the dog image, which on their demo appears to be identical to the original. Now look at it at 100% scale: http://imgur.com/z12mHnd http://imgur.com/z12mHnd . Block artifacts galore. Now sure, it may still do a better job than just choosing a constant quality setting and applying it across the board. But the demo doesn't show us that. It doesn't even make the right kind of comparison. What we need is a comparison of choosing a single quality level, and using JPEGmini. To be useful, here's the kind of demo we'd need to see. On the right side: five JPEGs saved with JPEGmini, having a total file size of X, shown at 100% resolution. On the left side: five JPEGs saved with a constant quality setting, chosen so that the total file size is X, also shown at 100% resolution. Then we'd honestly know whether the program is worth using. My guess? Probably not. The train station image, for example, is so grainy that you can compress it to damn near 600KB (50% in GIMP) before the artifacts are really noticeable (and well beyond that if you scale it down to 25% afterward). So did JPEGmini's visual model detect this and cut the bitrate down accordingly? No, it decided that the image should be saved at the equivalent of 83%, making the file more than twice as large as necessary. And this is on an image that was presumably handpicked as a shining example of how well the product works. My guess is that if you just chose around a 75% quality setting and compressed all of your JPEGs that way, you'd do just as well as JPEGmini.
- bjornsing 14y ago
  I agree 100% on the proposed comparison. In fact I proposed the same for a fair evaluation of Beamr video above. :) For the rest, I have no idea. I've never used anything Beamr.
mgurlitz 14y ago
That's actually a very good analogy to why Beamr's "minimal bitrate for no quality loss" isn't groundbreaking at all, especially since there is necessarily quality loss in lossy H264 -> H264 encoding. 85% is already a quality number, saying relatively how much quality you are willing to give up for kilobytes in your output JPEG. Similarly, x264's CRF option is a quality number, saying how much quality you are willing to give up for bitrate. Inevitably Beamr will produce some files that are inefficient, as well as some files that have noticeable banding and banding. The difference is CRF allows adjustments.

mistercow 14y ago

I see now that this is what they purport to do. However I still maintain that the presentation is dishonest. Showing a comparison at 25% scale gives the impression that the tool is better at choosing "nearly lossless" setting than it really is. Look at the dog image, which on their demo appears to be identical to the original. Now look at it at 100% scale: http://imgur.com/z12mHnd http://imgur.com/z12mHnd . Block artifacts galore. Now sure, it may still do a better job than just choosing a constant quality setting and applying it across the board. But the demo doesn't show us that. It doesn't even make the right kind of comparison. What we need is a comparison of choosing a single quality level, and using JPEGmini. To be useful, here's the kind of demo we'd need to see. On the right side: five JPEGs saved with JPEGmini, having a total file size of X, shown at 100% resolution. On the left side: five JPEGs saved with a constant quality setting, chosen so that the total file size is X, also shown at 100% resolution. Then we'd honestly know whether the program is worth using. My guess? Probably not. The train station image, for example, is so grainy that you can compress it to damn near 600KB (50% in GIMP) before the artifacts are really noticeable (and well beyond that if you scale it down to 25% afterward). So did JPEGmini's visual model detect this and cut the bitrate down accordingly? No, it decided that the image should be saved at the equivalent of 83%, making the file more than twice as large as necessary. And this is on an image that was presumably handpicked as a shining example of how well the product works. My guess is that if you just chose around a 75% quality setting and compressed all of your JPEGs that way, you'd do just as well as JPEGmini.

bjornsing 14y ago
I agree 100% on the proposed comparison. In fact I proposed the same for a fair evaluation of Beamr video above. :) For the rest, I have no idea. I've never used anything Beamr.

mgurlitz 14y ago

That's actually a very good analogy to why Beamr's "minimal bitrate for no quality loss" isn't groundbreaking at all, especially since there is necessarily quality loss in lossy H264 -> H264 encoding. 85% is already a quality number, saying relatively how much quality you are willing to give up for kilobytes in your output JPEG. Similarly, x264's CRF option is a quality number, saying how much quality you are willing to give up for bitrate. Inevitably Beamr will produce some files that are inefficient, as well as some files that have noticeable banding and banding. The difference is CRF allows adjustments.