Similar vertical lines as those in post #230577 can be observed. They both are created using SAI and have 100% quality. Is there anything fishy about SAI, or specifically its JPEG compressing algorithm (SAI created PNG is ok, eg. post #230670 )?

Other SAI created JPEGs with noticeable vertical lines:
post #229420
post #229751
Similarities: JPEG with 100% quality

SAI created JPEGs without noticeable vertical lines:
post #229379
post #230351
post #229721
Similarities: Either re-compressed or directed exported as JPEG with 99% or lower quality

If you are an artist, do me a favor. Can you reproduce those lines if you draw something and save it in 100% JPEG with SAI? If you can, please fire a bug report to SAI developers.

can't reproduce by SAI downloaded from http://sai.detstwo.com/sai/

it's normal 100% quality setting is Luminance Quality = 100, Color componets quality =80
But you can set both of them to 100 manually or by choosing "original"

In both cases I don't see lines.
Example: (post #230705)
q100 (Lumi100, Color80): http://i.minus.com/iJlZrdVvmZawV.jpg
q100 (lumi100, color100): http://i.minus.com/iY4Lcb18Qn2P.jpg

fireattack said:
can't reproduce by SAI downloaded from http://sai.detstwo.com/sai/

it's normal 100% quality setting is Luminance Quality = 100, Color componets quality =80
But you can set both of them to 100 manually or by choosing "original"

In both cases I don't see lines.
Example: (post #230705)
q100 (Lumi100, Color80): http://i.minus.com/iJlZrdVvmZawV.jpg
q100 (lumi100, color100): http://i.minus.com/iY4Lcb18Qn2P.jpg

Great!

iJlZrdVvmZawV.jpg (Luma100 Chroma80) do not have those lines while iY4Lcb18Qn2P.jpg (Luma 100 Chroma 100) have. In this scenario, the lines are not noticeable in RGB colorspace (post #230577 is not that lucy) but they do appear in YCbCr (distributed in all three channels).

Thank fireattack for the bug reproduction and wonderful pics.

Hmm 1.1.0? But i doubt SAI is still updating.

And how to see a image in dif YCbCr channel (in PS or not?)

fireattack said:
Hmm 1.1.0? But i doubt SAI is still updating.

Um...No bug tracer, no offical forum on the main site... I sent an email. Hopefully, it will stop ruining your works in no time.

The author Koji Komatsu is investigating on this problem now(13-11-2012).