Re: Image Question

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From: Cor (non_at_non.com)
Date: 02/16/04 

Date: Mon, 16 Feb 2004 21:08:52 +0100

Hi Trev,

The meaning of this thread is not the information, but the way we give
answers in this newsgroup.

But thanks for the information, because it added something again to mine and
I it makes things I was not sure of more sure because you read the same.
(It interest me, so it is not spoiled information)

And when I next time have a question like this, I take your advice and go
directly to Bob Powell in the drawing group.

And read my last answer to Herfried. Than all comes more clear.

:-)

Cor

> I did mention that I didn't know too much about Image conversion, but here
> are a few conditions under which you may loose data:
>
> 1) Changing from a "lossless" format to a "lossy" format (e.g. Gif to
Jpeg -
> Gif stores an exact replication of the image data, but JPEG compression
> results in smaller sizes because it discards data that it thinks isn't
> important)
>
> 2) Changing the color depth of the image (e.g. 24 bit PNG to 8 bit gif -
Gif
> only stores 256 colors, PNG can store 8 bit or 24 bit (or higher) images.
>
> 3) Changing between formats where the destination format doesn't support
> transparent colors.
>
> 4) Changing between a vector format to a bitmap format (e.g. wmf to gif)
>
> 5) Changing the resolution of the image.
>
> 6) Changing from a specialized format that stores data other than image
data
> (e.g. photographers name) or a format that can hold multiple images (e.g.
> Icon) to another format that doesn't support these features.
>
> These should be the only types of conditions that you could "loose" data.
> You shouldn't be loosing any by storing it in a BLOB (assuming there's no
> bugs in your database code ;)
>
> From what I understand from your conversion, changing from GIF to PNG
> shouldn't cause you to loose any data (although the PNG compression could
> result in fewer bytes in some cases)
>
> A better group for this might be microsoft.public.dotnet.framework.drawing
> or a more generic image convcersion group as you problem seems to be with
> changing image formats, not the storing of data in BLOBS or other files.
>
> Hope this helps,
>
> Trev.
>

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