[Mapserver-dev] problem with the quality of scanned maps

[Frank Warmerdam]

Jordi Valls wrote:
> Hello mapserver users,
> 
> I am working with mapserver and I am very satisfied with the software. Now I
> have a problem:
> My organization is interested in showing scanned maps from historical urban
> planing. The scanned maps, in jpg format, look fine with Arcmap(the esri
> product). But when I put them in mapserver, using the tileindex utility o
> not, the quality of the image  is not good. What can I do to improve the
> quality of the image?.

Jordi,

I think this question really belongs on the mapserver users list.  I
would also suggest you try and be more specific about the quality not
being so good.

I suspect the problem is that you are generating 8bit output from
24bit color jpegs and the simple color cube based downgrading is not
producing appealing results, but some examples would help us determine
if that is the issue.

The possible solutions include:
  o Turn on dithering for the layer (PROCESSING "DITHER=YES")
  o Generate 24bit output instead of 8bit.
  o Preprocess your jpegs into 8bit with external tools.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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