JPEG output quality

I’ve been playing with JPEG output quality on some old 6 meg files from a Canon 50D. At 10% output, the file size is only 400K , but the quality is very poor; Pixelated and posterized; so poor I wonder why it’s even offered as an option. However, when 50% output is compared to the normal 90%, the quality differences can only be seen at 400% magnification and they are not bad; slight artifacts on the edges of lines and posterization that takes a critical eye to see. Furthermore, file size is only 1 meg.

Storage is cheap and plentiful, so file size is not an issue, but performance, particularly with older computers is an issue: smaller files process more quickly. Why do we output at 90% when 50% is adequate for all but the most discerning eye?

Because 90% is “better” than 50%! But actually a good question. Most people (including me) haven’t done a detailed comparison of image quality at different compression levels. I usually use 90% but not due to a careful analysis.

It’s kind of up to us to use the settings we’re given adequately for the quality we want.
50% may be good for a simple JPEG to show on a tablet screen, 90% for some mid-size prints.
10% may also be great for my grandma’s phone. I see no reason why any portion of the scale should be restricted.


I experimented with different %s and finally settled on 95% as a compromise between 100% (which is unnecessary, as Jim found) and reasonable file-size.


Some time ago, I spent time to make tests with jpeg settings. In my experience, not noticeable, zooming at 100 % on the screen and comparing with tiff with FSV, above 60%. Also jpg by dxo are larger than those of other softwares, especially at 100 %.

The required “quality” also depends on the image. For example, sharp, high contrast edges create more visible artifacts at lower quality.


i did the same test in pl2 came up about 95% ( as not bigger size then original oocjpeg) and somehow my export in v3.2 and v4.1 is now settled at 90% there default i think.

i am quite lazy in exporting jpegs because i just watch them on a smart tv and 90% default is ok.
if i need something else i just re export to those parameters because i keep all rw2’s and developement dopfiles.

I think walking to the edge of reasonal possible quality around 95% is the tip over. no more improvement just adding more data aka bigger filesize.
Maybe when you play with the bicubical sharpening and iic profiles settings the quality-slider needs adjustment to gain maximal profit of the settings. don’t know.

anyway, it’s easier to settle for 90% because that’s what every upgrade is resetting to.

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