Yes they do, but then the image file size triples to around three times the original. So after I've scaled, (I do use scale) I do a Quantize back to 16 colours; it is then the problems occur. The 16 colours chosen are not those in the original colour map. Is there a way around this?
Angela -----Original Message----- From: Dermot Paikkos [mailto:[EMAIL PROTECTED] Sent: 09 June 2006 10:50 To: Angela Slaney; [email protected] Subject: Re: [magick-users] Problems Resizing Gifs with a colour depth of 16 I am not entirely sure I am that I am doing what you want but if I use -scale 480x480 the colours appear okay to me. I suspect that is what a browser is doing when it scales a image. "-scale uses a simpler, faster algorithm, and it ignores the -filter selection" there is a perlmagick scale method too. HTH. Dp. On 9 Jun 2006 at 10:19, Angela Slaney wrote: > Hi, > > I'm using PerlMagick version 6.2.8 on my server. > > I'm grabbing non-copyright wind-speed analysis images with a colour > depth of 16. An example original image is here at > http://activitae.com/images/wind.gif > > I need to reduce the image in physical size and, hopefully, byte size > too to display on smartphones or PDAs. > > When I grab an image and try to keep the colour depth the same I end > up with an image with grubby brown colours whereas they were yellow, > orange and red. Example http://activitae.com/images/wind1.gif > > > I've read the archive's previous posts about the file size of gif > images ending up larger than they started because of artifacts added > during resizing. And this certainly happens with these reduced colour > depth images, although I have had good results using perlMagick to > resize other web images. But these end up being 12Kb larger than the > original despite being reduced to 71%. > > The problem seems to be that Resize and Sharpen return the image to a > 256 colour depth. And then a Quantize back to 16 seems to choose any > colours in the image. > > My question is this is there a way to restrict the Resize and Sharpen > functions to only use the original image's colour table so I end up > with an image with correct colours and of smaller file size? > > And second question. If I handle an image request by passing back a > web page with <img src="http://...."; height='483' width='483' > the > browser then does the work of image reduction but appears to do it far > better than PerlMagick does. Example is here > http://activitae.com/NApda-2.htm . Is someone able to explain to me > why? > > All help appreciated. > > Angela > > > _______________________________________________ > Magick-users mailing list > [email protected] > http://studio.imagemagick.org/mailman/listinfo/magick-users -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.394 / Virus Database: 268.8.3/359 - Release Date: 08/06/2006 _______________________________________________ Magick-users mailing list [email protected] http://studio.imagemagick.org/mailman/listinfo/magick-users
