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Poor export quality for large images and yellow horizontal lines

May 04 2010 | 3 comments
Categories: Publishing

I'm creating a large output (90"x55") in ArcMap for printing on a poster and have been testing the results on a letter-sized version of the same page. The exported jpeg of the letter-sized area with 500 dpi at the correct scale looks wonderful. The problem is the output quality is bad when I export as jpeg from the full version, even though the file statistics show that it has the correct number of pixels to achieve 500 dpi across the large area. It also has a number of yellow lines running horizontally across the image. Suggestions?

Mapping Center Answer:

There may be a number of causes.

Let's base one cause as problems after exporting files for print. And this of course varies from printing device to device. But generally, what you are describing has a strong possibility of being a printer memory issue.

The first indicator is the banding that you are seeing in as "the number of yellow lines running horizontally across the image". Since you are trying to print to a magnitude larger, printing a test page at letter size is just a first step. Then, having already looked at the file statistics you need to to examine the printer device information itself. Does it have enough memory to handle the jpeg file and print instructions? Have you tried this size of file before? Is it spitting out an error file anywhere else (check and clear the TEMP file of previous attempted prints)?

Without knowing what your print setup is, we are limited in commenting further.

exporting rather than printing? posted by Jodi Norris on May 12 2010 12:24PM
Thanks very much for the reply, I am a little confused because for the export process I don't use a printer and just have a custom page size selected and select export as jpeg and don't use the print option. I have substantially increased the virtual memory of the machine, but that was for issues with another program, and this hasn't made a difference in the export quality since then. Is there a way to select the print device for an export? It does take about 2 days to do the export, and each time I restart the computer and leave everything else closed before starting the export - I usually try to leave it for a weekend. I also had this issue when exporting it to a pdf and TIFF and again the quality was very poor on the large page size. I could try printing to an eps file and use arcpress?

Additional information: there is a partly transparent hillshade layer on the map, and the areas that have particularly poor quality correspond to areas with more hillshading. areas with less hillshading look pretty good. It is confusing that the heavily hillshaded areas have good quality on the letter-size map.

Also the annotation doesn't have the bad pixelation effects on either version.
Solution / work around to yellow lines and pixelat posted by Jodi Norris on Jan 5 2011 8:00AM
These solutions worked in ArcGIS 9.3, I don't know if the same problem exists in very very large exports in the new ArcGIS.
As far as I can tell, the issues related to the 1) the partly transparent hillshade layer and 2)the catalog management. Indicators were that the pixelated effect occurred only near areas of high topography, which relates to the transparent hillshade, and that the yellow lines were on the boundaries of the catalog images. The painful solution to the problem of pixelation: - I downloaded the zoom and export script and used a mapbook grid to export the partly transparent hillshade overlaid on the imagery in many many pieces. then created a separate image catalog of that (see below for catalog info). Then loaded that catalog onto my final map with annotation etc, so that the final mxd did not have a transparency set on an image layer. The result was really beautiful and worth it. Solution for the yellow lines: there might be others, but I created a personal geodatabase (mdb), and created an unmanaged catalog and loaded images into that. I tried three alternatives to this method, including mosaicking and other catalog types and either still got the yellow lines or the process froze.
Additional thing - resaturate the image posted by Jodi Norris on Jan 5 2011 8:09AM
I used the free command line program Imagemagick to resaturate the final export image colors because they look washed out after applying the hillshade transparency.

using
convert input.jpg -set option:modulate:colorspace hsb -modulate 140,160 -limit memory 900MiB Output.jpg

This increases saturation a bit beyond normal because we wanted a pleasing print. It also increases brightness strongly because this particular plotter printed darkly.

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