Hi all,

I'm using pcolor (with interpolated shading) to create a figure.  My goal is to then use Adobe Illustrator (CS3) to produce a publication-quality graphic.  

The figure that Matlab produces looks great, but once I save the image in EPS or PDF format, the quality goes down considerably.  The image is crisscrossed with white lines that form triangular polygons.  I guess those are the primitive objects that were used to draw these particular vector graphic images.  Unfortunately, it looks awful.

I've tried saving the Matlab output in Illustrator format and then opening this file in illustrator, but the results are terrible - the image looks very blocky.  Saving the Matlab output as a bitmap doesn't seem to work, either.  The quality is too low. 

Is this just a data resolution problem?  That is, should I try and get data that is better resolved before plotting this image?  Any suggestions are very welcome!

"Dan Jones" <Daniel.Jones@colostate.edu> wrote in message <hqpv1p$hi$1@fred.mathworks.com>...
> Hi all,
> 
> I'm using pcolor (with interpolated shading) to create a figure.  My goal is to then use Adobe Illustrator (CS3) to produce a publication-quality graphic.  
> 
> The figure that Matlab produces looks great, but once I save the image in EPS or PDF format, the quality goes down considerably.  The image is crisscrossed with white lines that form triangular polygons.  I guess those are the primitive objects that were used to draw these particular vector graphic images.  Unfortunately, it looks awful.
> 
> I've tried saving the Matlab output in Illustrator format and then opening this file in illustrator, but the results are terrible - the image looks very blocky.  Saving the Matlab output as a bitmap doesn't seem to work, either.  The quality is too low. 
> 
> Is this just a data resolution problem?  That is, should I try and get data that is better resolved before plotting this image?  Any suggestions are very welcome!

Try to produce publication quality bitmaps direct from Matlab using export_fig from the FEX.

Hi - 

The problem you mentioned (the "white crisscrossed lines") frustrated the hell out of me for a while. As far as I can tell, the problem lies not with MATLAB's image rendering but rather with the anti-aliasing routine used in most PDF/EPS viewers. In other words the output from MATLAB is fine but the PDF viewer is not rendering the image correctly. If you can find a way to turn the anti-aliasing (in your PDF/EPS viewer) off, I think the problem will likely go away. E.g. if you are using Adobe Reader: go to Preferences > Page Display > disable the "smooth line art" setting. This sorted out the issue for me!

"Dan Jones" <Daniel.Jones@colostate.edu> wrote in message <hqpv1p$hi$1@fred.mathworks.com>...
> Hi all,
> 
> I'm using pcolor (with interpolated shading) to create a figure.  My goal is to then use Adobe Illustrator (CS3) to produce a publication-quality graphic.  
> 
> The figure that Matlab produces looks great, but once I save the image in EPS or PDF format, the quality goes down considerably.  The image is crisscrossed with white lines that form triangular polygons.  I guess those are the primitive objects that were used to draw these particular vector graphic images.  Unfortunately, it looks awful.
> 
> I've tried saving the Matlab output in Illustrator format and then opening this file in illustrator, but the results are terrible - the image looks very blocky.  Saving the Matlab output as a bitmap doesn't seem to work, either.  The quality is too low. 
> 
> Is this just a data resolution problem?  That is, should I try and get data that is better resolved before plotting this image?  Any suggestions are very welcome!

I spent some time dealing with this problem today and I couldn't figure out how to change the anti-aliasing (I'm using Inkscape, maybe there's a way to do it?). Eventually I stumbled on a simple but not very elegant solution: 

1. open the .eps file
2. ungroup everything: after 3-4 ungroups I had it down to a layer in which all of the triangles can be selected with a single click.
3. copy the triangles and paste in place a couple times. The lines get fainter and disappear eventually. 


"Vinesh Rajpaul" wrote in message <i1g11s$jt9$1@fred.mathworks.com>...
> Hi - 
> 
> The problem you mentioned (the "white crisscrossed lines") frustrated the hell out of me for a while. As far as I can tell, the problem lies not with MATLAB's image rendering but rather with the anti-aliasing routine used in most PDF/EPS viewers. In other words the output from MATLAB is fine but the PDF viewer is not rendering the image correctly. If you can find a way to turn the anti-aliasing (in your PDF/EPS viewer) off, I think the problem will likely go away. E.g. if you are using Adobe Reader: go to Preferences > Page Display > disable the "smooth line art" setting. This sorted out the issue for me!
> 
> "Dan Jones" <Daniel.Jones@colostate.edu> wrote in message <hqpv1p$hi$1@fred.mathworks.com>...
> > Hi all,
> > 
> > I'm using pcolor (with interpolated shading) to create a figure.  My goal is to then use Adobe Illustrator (CS3) to produce a publication-quality graphic.  
> > 
> > The figure that Matlab produces looks great, but once I save the image in EPS or PDF format, the quality goes down considerably.  The image is crisscrossed with white lines that form triangular polygons.  I guess those are the primitive objects that were used to draw these particular vector graphic images.  Unfortunately, it looks awful.
> > 
> > I've tried saving the Matlab output in Illustrator format and then opening this file in illustrator, but the results are terrible - the image looks very blocky.  Saving the Matlab output as a bitmap doesn't seem to work, either.  The quality is too low. 
> > 
> > Is this just a data resolution problem?  That is, should I try and get data that is better resolved before plotting this image?  Any suggestions are very welcome!

This is a nice little workaround.

If you have Microsoft PowerPoint, it views it properly!

So save your pcolor figure to *.eps.

Then drag it into PowerPoint. In PowerPoint, right click the imported picture and Save As as PDF.

Illustrator can then open this, and the lines are gone!

~Ward

This problem has been bugging me for years!  Finally, due to this thread, I have it fixed.  In Illustrator go to Preferences > General, and deselect Anti-aliased Artwork.  Finally!!  Thanks, All.

"Dan" wrote in message <jireu0$71g$1@newscl01ah.mathworks.com>...
> This problem has been bugging me for years!  Finally, due to this thread, I have it fixed.  In Illustrator go to Preferences > General, and deselect Anti-aliased Artwork.  Finally!!  Thanks, All.
--------------------------------------------------------------
The problem that's been bugging me for years is why anyone would ever want to use pcolor in the first place since it's so deceiving in that it has one less square in each direction than the number of elements in your array and the colors in it don't correspond to your array values.  I've asked many times but have never gotten an answer of any kind.

Unfortunately, if the problem lies in every viewer's default anti-aliasing settings, then you would guess that inserting the Matlab PDF of a surf() plot into a publication will have white lines all over it for almost all readers of your paper!  

It doesn't really help for only you to remove the lines - unless a subsequent "Export > *.TIFF" does in fact remove the lines.  It would have been nice to retain the PDF format though, for zoomability.