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rflynn / imgmin

Lossy image optimization
MIT License
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Progressive JPEG #41

Closed szepeviktor closed 9 years ago

szepeviktor commented 9 years ago

Is it possible to convert to progressive JPEGs?

I think convert -interlace JPEG after-imgmin.jpg output.jpg will degrade quality.

szepeviktor commented 9 years ago

WebPagetest now warns you for any JPEGs that are not progressive.

szepeviktor commented 9 years ago

For example jpegtran does it jpegtran -perfect -optimize -progressive -outfile output.jpg after-imgmin.jpg

rflynn commented 9 years ago

I tried this out and got worse results. Update to the latest imgmin again and see what you get.

[rf@Ryans-MacBook-Pro ~/src/imgmin/examples]$ ls -l Afghan-Girl-by-Steve-McCurry* | awk '{print $5,$9}'
30286 Afghan-Girl-by-Steve-McCurry-after.jpg
60198 Afghan-Girl-by-Steve-McCurry.jpg
[rf@Ryans-MacBook-Pro ~/src/imgmin/examples]$ jpegtran -perfect -optimize -progressive -outfile Afghan-Girl-by-Steve-McCurry-after-jpegtran.jpg Afghan-Girl-by-Steve-McCurry-after.jpg
[rf@Ryans-MacBook-Pro ~/src/imgmin/examples]$ ls -l Afghan-Girl-by-Steve-McCurry* | awk '{print $5,$9}'
31067 Afghan-Girl-by-Steve-McCurry-after-jpegtran.jpg
30286 Afghan-Girl-by-Steve-McCurry-after.jpg
60198 Afghan-Girl-by-Steve-McCurry.jpg
szepeviktor commented 9 years ago

Thank you. I will report v1.1 experiences. Progressive JPEGs are also important for visitors, they load nicely.

szepeviktor commented 9 years ago

Honestly I switched to https://github.com/danielgtaylor/jpeg-archive because you can select image comparision method an you have mozjpeg and the output is always progressive. Please consider examining it.