Black Dot Issues?

Started Dec 10, 2008 | Discussions thread
eeguy New Member • Posts: 3
Re: Black Dot Issues?

As an engineer in the software and electronics field I'll weigh in here that the black spot problem is a software issue and not the sensor. Some will comment that "hey it is in the RAW file" but RAW isn't as virgin as you might think. There is definitely software pulling data from the analog to digital converters and any engineer will tell you there are lots of tricks in turning sampled sensor data into the first pass usable output. If this were purely a sensor issue, I wouldn't expect it to be limited to one side of the bright areas. Looking at the silicon design it seems extremely unlikely that the source of the problem resides there.

This clearly looks like a rasterizing artifact deep in the bowels of the sampling code. We used to experience a problem that looks surprisingly like this in a process called error diffusion. Accumulated error is mixed with subsequent raster lines to smooth it out. If you aren't careful however, the error can "roll over" registers in the processor and suddenly day becomes night. Maybe the clever engineers at Canon have something similar in their ADC processing. A/D converters always have inherent + - error in sampling so it is entirely possible this is the case.

Anyway, I'm sold on the camera and I think in a couple of months this will probably be solved with a firmware update. I wouldn't expect an immediate fix as most firmware updates go through significant regression testing prior to release.

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