"Real WMV", 148.50 mhz sample-rate, 1920 X 1080 progressive scan image, "object data" bit-rate of 1-

[Lionel]

Lionel said:
Wrong. The more you (lossy) compress the colour-depth, the more
posterised & jaggy the image becomes. This is the direct consequence
of the process Bob is describing.

Pete replied:
Depends how you do it.
For example, I could easily reduce the bit depth on an
image to 1 bit per channel, using error feeback, and the
image would be neither particularly posterised nor jaggy.

Lionel replied:
Of course it would be. Reducing the bit-depth of any typical movie
frame from 32 or 24 bits to 1 bit will always posterise it.

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Pete:
That's not true. Reducing the bit depth of a 32 or 24 bit image to
one bit will convert it to monochrome, but it need not posterize
it. Just take the error caused by reducing the accuracy of
each pixel, and add it on to the next pixel.

It's called error feedback. Try Googling it.

I understand what you're saying, but what you're missing is that if
you add error feedback, the colour-depth can no longer be said to be
reduced.

 

[Pete Fraser]

I understand what you're saying, but what you're missing is that if
you add error feedback, the colour-depth can no longer be said to be
reduced.

Yes it can.

If I take a 1024 x 1024 x 8 monochrome image, I can apply error
feedback and reduce it to 1024 x 1024 x 1 using error feedback.

I have taken 1 MB of data, and reduced it to 128 kB.
If that doesn't fit the definition of a 1-bit color-depth, I don't know
what does.

There will be no posterization.

 

[Gene E. Bloch]

Yes it can.

If I take a 1024 x 1024 x 8 monochrome image, I can apply error
feedback and reduce it to 1024 x 1024 x 1 using error feedback.

I have taken 1 MB of data, and reduced it to 128 kB.
If that doesn't fit the definition of a 1-bit color-depth, I don't know
what does.

There will be no posterization.

I bet that decent (monochrome) dithering could also give a result of
reasonable quality, but I admit that this is speculative.

 

[Pete Fraser]

On 10/31/2006, Pete Fraser posted this:

I bet that decent (monochrome) dithering could also give a result of
reasonable quality, but I admit that this is speculative.

What I describe is a simple form of dithering. You can get more
sophisticated (by using 2-D error feedback schemes such as
Floyd-Steinberg or similar), but yes; you are dithering.

 

[Gene E. Bloch]

What I describe is a simple form of dithering. You can get more
sophisticated (by using 2-D error feedback schemes such as
Floyd-Steinberg or similar), but yes; you are dithering.

Thanks for the info; looks like I had a not too off-the-wall
understanding of what you were describing.

OT: Did you mean to make a pun about dithering? I have occasionally
been accused of dithering