parallelization - Raster with ColorFunction is blank when Dynamic Updating is disabled

UPDATE

Today I was having these WaveletScalogram problems again. I think this is ultimately some kind of interaction issue with Dynamic. I have narrowed it down to this:

Graphics[Raster[{{0}}, ColorFunction -> "AvocadoColors"]]

Run this line, and then disable Dynamic Updating ("Evaluation" menu) and run it again. On my computer it comes out blank when Dynamic Updating is disabled. If you remove the ColorFunction option, it will work fine with or without Dynamic Updating. So new question: Why does this happen? Is it a bug? I wonder if others can even reproduce this.

Previous version of this question:

I was trying to export WaveletScalogram plots (to image formats) in parallel, and some of the images were coming out blank. I've managed to reduce the issue to what appears to be quirky Rasterize behavior on WaveletScalogram plots specifically, in parallel computations. I'm on version 8.0.4.0 on Win7 64. With the following:

ParallelTable[

 Rasterize@
  WaveletScalogram[ContinuousWaveletTransform[RandomReal[{0, 1}, 2000]]],
 {f, 4}]

I get:

enter image description here

Change ParallelTable to Table, or remove the Rasterize, and I get:

enter image description here

I'm just wondering if this is actually a bug or I'm just missing something.

update

I was able to get it to work by hard-limiting the number of kernels to the number of cores on my system (a monstrous 2 cores). The "Parallel Kernel config" is a little confusing in this regard, since I have to set it to "1 parallel kernel" to get 2 parallel kernels controlled by a 3rd master kernel O_O Still this Rasterize behavior is uncalled for, I think.

Comments

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