Bad quality decoding JPEG files

[Xn User]

Hi )
XnConvert and XnView MP have is bad quality in decoding from JPEG files

Previous I considered the issue in the topic viewtopic.php?f=79&t=48274&p=202831#p202831 , but all still worse than I thought )

Giant_planes_comparison.svg - original picture
svg_to_bmp.bmp - this is transcoding from SVG to BMP in XnView MP
bmp_to_jpg.jpg - this is transcoding from BMP to JPG in XnView MP with maximum quality for JPEG plugin all set on maximum quality
from-jpeg-to-bmp-xn.bmp - this is backward transcoding from JPEG to BMP in XnView MP
from-jpeg-to-bmp-acd.bmp - this is backward transcoding from JPEG to BMP in ACDSee Pro 8

If compare images , so can see diffirence in colors in original and XnView MP , but this diffirence absent if compare original and ACDSee Pro

PSNR if compare svg_to_bmp.bmp to bmp_to_jpg.jpg - 59,81
PSNR if compare svg_to_bmp.bmp to from-jpeg-to-bmp-xn.bmp - 36,8
PSNR if compare svg_to_bmp.bmp to from-jpeg-to-bmp-acd.bmp - 59,81

That's why I think , what need increase quality JPEG decoding in XnView MP and XnConvert )

Also digital noise in XnView MP /XnConvert make files bigger if perform transcoding to any other compression format )

This is happening if use progressive compression ) , backward transcoding from progressive JPEG not coincide with original JPEG file and transcoded JPEG progressive to BMP file