Is There a Recommended Quality Setting for JPEG Images?

[bytesource]

Hi,

For my website, currently located at http://staging.sovonex.com, I have been using jpeg images at the following quality:

1. Cropped in GIMP and exported using the "Save for Web" plugin with a quality of 85%
2. Most images are further resized in Processwire with an image quality of 90% and sharpening set to 'soft'.

In order reduce page load times (*), I was wondering if setting the quality below 90 would be appropriate. The problem is that I have not the eye of a photographer, and some of the images on the site are not high quality shots to begin with, so I have problems figuring out the best quality setting. With 'best' meaning in this this case, the lowest quality at which the image still looks fine.

On the web have found posts stating that setting the quality to 85 was the best choice most of the time. But then again I already saved the original with a quality of 90, so I am not sure if this "rule" was still applicable in my case.

(*) I am currently trying out different options for serving adaptive images, that is serving images with sizes based on the size of the screen they are viewed on. So here I only want to ask about the recommended image quality.

Cheers,

Stefan

[horst]

Hi Stefan,

image presentation on the web is a compromise between less loading and good image quality. If you can avoid to show the original image at the front end I would recommend to use those "only as resources" for the derivatives that are shown to the public. This way you should use the best quality for the original images, 100% quality, saved as default.

Optimized Jpegimages have artefacts, more or less, depending on the quality setting. If you use an image that has already artefacts (q90 optimized for web) you will become artefacts of the artefacts, but at least more artefacts as from a resource image with q100 saved default.

Which finally quality setting is usefull for your images you only simply can try out. I believe that you can use between 80 and 90 with good quality.

[bytesource]

Hi Horst,

Thank you very much for this valuable information! I will try to find the 'perfect' quality setting within the 80 to 90 range you mentioned.

Cheers,

Stefan

[pwired]

Use a jpg compressor and move the slider until the point where

the picture starts to look bad. Then move the slider a bit back.

The eye can´t see the difference from the original but the size

has become significant lesser. http://winsoftmagic.com/ajc.html

[bytesource]

@pwired

That is a good idea! Thank you very much!

Cheers,

Stefan