Dithering nuisance

[AndyF]

Hi all:

I've saved my page size 8.5 X 11 in PNG format. The images are all cleaned and sharp and I have no

residual particles remaining on the saved file and not visible in screen resolution even in zoom mode, so I know the file is not corrupted.

The problem is I still get dithering even though I'm saved to 32bit PNG with the greyed-out dithering gauge set at zero. I read

that PNG should offer up to 64K color palette/pixel, and that should prevent dithering. My text, which is graphic text, is better

that in BMP also, but not the best.

What I would like to get is RAW, or WSIWG. I don't really care about file size has I have gobs of gigs.

I started working in BMP and I think that was 16 or 24 bit. Then I went to PNG and is an improvement, but I

need best quality. I'm printing on a samsung lazerjet, and I am capable of getting photo quality out of it.

Any help would be appreciated.

Thanks,

Andy

[Rick Brewster]

Dithering is only applied when saving as 8-bits per pixel.

At 24- or 32-bits, PNG supports 16.7 million colors. 32-bit includes an alpha channel. If you want 64-bits per pixel, that is not possible in Paint.NET, and probably wouldn't help anyway.

[AndyF]

Thanks Rick.

I notice we have DDS and PDN formats. I'm not familiar with these. But if they offer not attempt

at compression, maybe that's what I need.

Thanks.

Andy

[Rick Brewster]

If you're saving single-layer images as PNG, that'll be perfect.

Image compression comes in two forms. Lossless compression, which PNG uses, won't affect fidelity. It's like a ZIP file: if the contents get changed, then there's a bug or something's failing with respect to hardware (bad disk or network card usually).

Lossy compression, like JPG, will remove fidelity in order to achieve lower file sizes.

As long as you're saving as PNG or PDN, then any dithering or fidelity loss is going to be from the source image itself.

DDS (DirectDraw Surface) is for games. Generally, only use that if you're doing game related stuff.

[BoltBait]

I suspect that the problem is that you are scaling a small graphic up to something larger when printing.

Try creating the image with a higher dpi.

[AndyF]

Thanks guys for the tips.

You'd a thought by now MS would have dropped auto compression and made it optional

now with all the advances made in micro technology.

I mean sacrificing quality for compression is just not priority stuff anymore IMHO.

Andy

Edited May 26, 2011 by AndyF

[Rick Brewster]

Compression doesn't necessarily entail any loss of fidelity (and/or dithering). PNG will not lose any fidelity. I suspect the problem you're seeing is due to some other cause.

[AndyF]

Thanks Rick.

While searching for a solution on the web, a few people had similar problems. While they weren't using P.N, they had come to discover that it was

related to the transparency setting of the background in their images. I wonder if this is a place to look for me. My picture has only a background, so I

don't know if it could help me if at all.

Andy