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Downscaling artifacts in red channel. Why? (Algorithms)?

When I view pictures in digital camera (Canon 125 HS) bright red color seems to be really pixelated.

When I view Youtube video:

Example: devinsupertramp - Dubstep piano on the lake watched in 360p

http://youtu.be/01jgYIZfHrM?t=54s&vq=medium

On bright red areas resolution is clearly half of resolution of overall video:

http://puu.sh/8IBYR.jpg

It becomes even more evident when viewing only red channel:

http://puu.sh/8ICgE.jpg

Recently this new artifact seems to be visible in many places. Before I have newer seen it.

This is mystery for me.

Update:

Reupload of first example picture:

http://puu.sh/8ICUN.png

1 Answer

Relevance
  • ?
    Lv 7
    7 years ago

    In all likelihood this is due simply to jpeg compression and has nothing to do with normal downscaling algorithms by themselves...

    Jpeg compression attempts to account for the sensitivity of certain colors to the human eye.

    here's some info

    http://www.jpegcruncher.com/

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