Have there been changes in image compression recently?

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1

These is a recurrent topic.
We have been having problems with image compression previously, as there seems that the software tries to compress each image uploaded by the users.

We are a photography forum and our users complain about their photos loosing quality (they loose quality indeed).

Till now we have circunvented it changing compression parameters. We have stablished a threshold of 1.2 MB and 2000 px width.
Images that are less than 1.2 MB in weight and 2000 px size should not be recompressed before uploading and only images that exceed that should be recompressed.

But lately we are having complains of users that say that their image is slightly recompressed even when te image is less than 1.2 MB and 2000 px width.

Has there been any changes in composer working?

Is there any way to be sure that images which complain with that parameters are not touched or recompressed by the system?

Thank you for your help.

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2

Make sure you have recompress original jpg quality set to 100, this one bit me for a long time and I just figured it out.

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Thank you, I will try.
I had it set to 97, I had thought that recompress was only activated when the image exceeded image thresholds.

I have configured composer media parameters like this (I don’t fully understand the meaning of all of them):

image bytes optimization threshold: 1259520 (a bit more than 1,2 MB).
image resize dimensions: 2000
image resize width target: 1920
optimization image encode quality: 97

So you say that I have to change it from 97 to 100.

But shouldn’t it be applied only when the images exceeds thresholds?

If I use 100 it won’t be able to resize the image bellow thresholds, would it?

Thank you for your help.

4

From what I understand and verified in my testing is that the recompress original jpg quality setting will resample the image no matter what if it is set below 100.

max image size kb is what will trigger a resample if it’s over this size, even with the above setting at 100. Both of these happen server side.

composer media optimization image enabled happens client side and will resample an image before it’s even uploaded. I turned this setting off because it strips the metadata, it might be doing some resampling in your case too.

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Well, thank you so local optimizaciĂłn should be off and 100 the recompress factor.

I gave to donsomebtests ti see hoy all these work It seens complucated and not ideal

If imagen comoky ti the limita they should not be toyches and only compressed to the target size when they exceed the limit in size or weight.
That is what i has understood but It seems that does not work that way.

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6

Hey @ariznaf :slight_smile:

Could you share a link to an original picture < 2000px and < 1.2 MB, and to the recompressed one after upload?

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Thank you, I will try to, I have to make tests on my own to see if the files Yolanda added are changed when they comply with the thresholds, I have several people complaining about It but I could not corroborate it by myself. If I find an example I will provide it.