Picture Field

[Ruslan Zasukhin]

On 3/15/10 9:00 PM, "Thomas Flemming" <tf at ttqv.com> wrote:

Hi Thomas,

> I'm saving .Net-Bitmaps with PixelFormat=Format8bppIndexed
> the a picturefield with
> fldBmp.WritePictureAs(bmp, EVPictType.kTIFF).
> 
> When I read the bitmap later with:
> Dim bmp As Bitmap = fldBmp.ReadPicture
> 
> I realized, that the bitmap now has a PixelFormat=Format32bppRgb
> 
> Since I need to take care of the size of the database, how is my 8-bit-Image
> actually stored in the database? 8-bit or 32-bit? Are you also using a
> tiff-compression?

You have asked to save them on disk in TIFF format.
 
Not remember about compression for TIFF.
Should be checked.

----
> Another question is: the picture-field has the flag "compression" set to true,
> meaning, that the tiffs are nicely compressed.

> But some pictures are better saved as jpg. So when I save a bitmap with
> fldBmp.WritePictureAs(bmp, EVPictType.kJPG), will the database still try to
> compress it? This would be useless, since jpg is already compressed best.

Do you talk about VBLOB.compression flag?

This flag enabled ZIP compression for general BLOBs.
You should not use this flag for PICTURE field.
Because really and TIFF and JPG have better compression than ZIP.


-- 
Best regards,

Ruslan Zasukhin
VP Engineering and New Technology
Paradigma Software, Inc

Valentina - Joining Worlds of Information
http://www.paradigmasoft.com

[I feel the need: the need for speed]