yes i agree with mike. PCC uses 'aperture photometry' as a default method, meaning it has to detect stars and then compute an aperture for each star over which to sum the flux. i'm saying that PCC might be having problems 1) detecting stars in the image (as evidenced by the low star count and how hard it is to solve this image) and 2) computing correct apertures for the detected stars due to their profiles.
the 'detected stars' map is going to show you what stars PCC identified for photometry. i think it's an important debug tool here - you can evaluate just how many stars it can detect, and which, to see if those stars have meaningful color data.
one possibility would be to perform deconvolution on the image in order to tighten up the stars, but you have to be careful there as the decon could saturate the centers of otherwise unsaturated stars, again perhaps throwing the PCC calculation off.
on the theory that you have saturated star data which has shown up as unsaturated pixels, it might make sense to run Rescale in individual channels mode on the image to get those saturated stars into the ~1.0 range. this is a longshot though because i am not sure if that really will cause PCC to exclude them. the heart of this problem is that DSLRs have 14-bit sensors and when PI reads this data in, it stuffs the data into the lower 14 bits of 16 bit integers. so saturated pixels in your original CR2 end up with a value of 0.25 or thereabouts in the 16-bit data. so the saturated pixels suddenly don't look saturated, but you can see that the stars are "flat" with your eye - the whole center of the star has a value of 0.25. what i am not sure about is if PCC can understand that the star data is no good in this situation, and so perhaps the rescaling would help it out.
rob
