JPEG compression making images larger

I know Squash 3 is still in beta, but it seems weird to me that the JPEG compression is so bad, that at 80% compression it manages to make the sample image larger.

Does anyone know why this is happening?

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The compression setting refers to quality, so 80% is high quality, I’d reduce it to 60% or less if you’re trying to make the image as small as possible :+1:

The split view is there to help you reduce the quality and compare with the original so you can make sure the image still looks great.

Hope that helps.

@dan: It still seems @JonasPedersen’s question is valid. Uncompressed his image is 997 kB, but with compression it is larger at 1.1 mb. So, why would compression make the file size larger than the original image?

If the jpeg quality on your “original” image is set lower than the quality of your converted image, the file size on the converted image will be larger. You can try this with any image editor. Save an image at 60% quality. Open that image and save a copy at 90% quality and your resulting file size will be larger.

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@YankeeLaker exactly as @DLH said :blush:

I guess this makes more sense now, that you’ve explained it, but it’s still a bad user experience to see an 80% compression make the image larger. Especially as the image I used for this example is the sample image from the Squash app. That image shouldn’t have been pre-compressed. Maybe the percentage of compression should be relative to the image used for a better user experience.
I also don’t remember Squash v2 to ever make an image larger with any percentage of compression.

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Squash 2 used the exact same compression engine for jpgs. So it was exactly the same :slight_smile:

Good suggestion on perhaps using a different image, we’ll get on that and as you say it’s not a great first run experience if the resulting jpg is bigger!!!

Cheers
Dan

I think the issue @JonasPedersen has is a fair one because the block is headed “Compression” even though the slider is labeled “Quality”.

Given the block will not always result in smaller file sizes I would like to suggest the block be renamed.

My suggestion is either “Conversion” or “File type”. As it is the only block which cannot be turned off, every file processed will potentially end up a different size than the original file and that could go either direction.

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As a user I wouldn’t expect an image to grow in size after compression. This would feel like a bug or poor compression if I were the end user. It would make sense what Squash should look at the resultant compressed file and if it is larger than the original it should revert to the original image. Just my view.

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If the resulting image is larger, then we show a yellow warning triangle with an info dialog if you click on it… We’ll make this more obvious in future builds.

This is what users will currently see:
Screenshot 2021-07-30 at 1.53.33 pm

Oh, we’ll also change it from “Compress” to “Convert” — Thanks for the suggestion @zkarj!

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@dan Hi, from a customer perspective, please just show a warning like “Image can not be compressed further” and leave it untouched. This is a cornercase and will not be seen many times. Please try to avoid many more questions or remarks - which you will have to catch by even more icons, error messages and so on. Go for the 98% of the users, not the 2%.

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It’s not as simple as that, it can almost always be compressed further for a smaller file size, however the quality may be unacceptable for the user. That’s what we have a split view so users can get the file as small as possible with the level of quality they are after.

We could drop it to 20% quality by default, this would result in smaller files 99% of the time, but as I said users may not be happy with the quality…

We have a few ideas to make this better, but these things take time.

I see, thanks :slight_smile:

Oftentimes I will have an image that is already a size/quality that I like, but just want to use Squash to add a consistent watermark. I would very much like to be able to turn compression off if I want to.

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