Matt Gruenke wrote:
Fernando Cacciola wrote:
Now, off the pixel/color topic. rom the Quicktime format disccusion: is it possible to supersample (rather than subsample) an image? That is, to take two or more consequtive pixels in a row and pretend is just one pixel?
You're talking about a subsampling (or decimating) iterator,
No, but I can see how the way I expressed it looked like that.
instead- of an interpolating iterator?
Exactly. The idea was not to skip even or odd pixels (which subsampling does) but to combine them. The actual N-1 mapping would be defined by the iterator: it could interpolate, add and clobber, concatenate or whatever makes sense.
I believe the code structures necessary for both of these tasks are largely identical - once you've worked out how to do one, the other should be quite straight forward.
However, for most purposes where this is desirable, it is probably more efficient to write a routine that resamples entire rows and columns at a time.
Which is what Ulrich said. It would be interesting the benchmark it though.
You'd be discarding information, though. The reason chroma has half the sampling frequency, in this case, is because it has been band-limited to half the bandwidth of luma (a perceptual optimization). If you decimate luma, you're going to loose information (given no assumptions about the input data). So, it's fails as a simplification, because it's not equivalent.
The above corresponds to a subsampling/decimating iterator right? I was referring to "combining" iterator. Would that work? Best -- Fernando Cacciola SciSoft http://fcacciola.50webs.com/