Opencv IMWRITE_JPEG_LUMA_QUALITY parameter doesn't work as expected in 3.2.0

C++
,
1

According to the documentation, the IMWRITE_JPEG_LUMA_QUALITY parameter is supported.

IMWRITE_JPEG_LUMA_QUALITY Separate luma quality level, 0 - 100, default is 0 - don’t use.

But I realized that when I set it to default 0 (don’t use), it still has an impact on the image. This is unexpected, if it’s set to 0, it shouldn’t have any impact on the image compression.

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Reference: OpenCV: Image file reading and writing

This is from the source code:

            if( params[i] == CV_IMWRITE_JPEG_LUMA_QUALITY )
            {
                if (params[i+1] >= 0)
                {
                    luma_quality = MIN(MAX(params[i+1], 0), 100);

                    quality = luma_quality;

                    if (chroma_quality < 0)
                    {
                        chroma_quality = luma_quality;
                    }
                }
            }
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