As I said, cutting the resolution to 150 dpi is possible, but shouldn't be necessary. The original art is actually vector art, but was created in RGB space with overlapping transparencies and blend modes. Illustrator's colot space conversion algorithm doesn't handle this well, since it first changes the color on a per-object basis, instead of per-pixel, then re-applies the blend modes - this results in unexpected color shifts. I had no problem opening the original composition in Photoshop at 300 dpi, then converting the flattened art. Photoshop is more graceful with big files, and allows me to choose from multiple algorithms for converting the color space. Sadly, it seems that I can't bring the converted art back into Illustrator. I'm going to see if the printer will accept a flattened bitmap instead of an Illustrator file. They don't handle InDesign files.
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