avoding interpolation all together

Does anyone know of a way to save dslr images without interpolating RGB? Like what If I just wanted to save the red channel to .tiff in monochrome without interpolating it? I have seen IRIS used for this process but it is a bit cumbersome and crashes when I try to load more than one image. It would be great if I could use a program with a GUI instead of command line to carry out the process. Any suggestions? I already have photoshop, camera raw, DPP. .. suggestions appreciated.

Raw digger.

http://www.rawdigger.c​om

dcraw

https://www.cybercom.n​et/~dcoffin/dcraw/

PixInsight

www.pixinsight.com

Raw Therapee

http://rawtherapee.com

Kirk

You sir, are awesome. Raw therapies looks awesome, is the process of saving non interpolated files pretty straight forward?

You do realise that by only using the data from one of FOUR channels in a RAW file you will lose 50% of your resolution. Add to that the AA filter is designed with colour interpolation in mind too, so will not be particularly efficient on a single colour channel, this means that you are quite likely to end up with aliasing on fine subject detail, even with quite mediocre lenses, let alone good sharp ones. I suppose you could try playing with both the green channels, but then you would still be back to having to interpolate the two offset grids to produce a useable single image matrix.

In order to be able to avoid interpolation completely, without sacrificing resolution, you would need to be using a monochromatic sensor with no Bayer CFA. Other than specialist scientific and engineering vision systems the only current camera that I can think of that allows this is the Leica M Monochrom. Personally I would expect the results of doing a normal conversion direct to monochrome in a good RAW processor to provide better results, even with the interpolation, than you would get from any of the single RGGB channels.

Is there a specific reason that you want to do this? I do understand that I just want to see is a good answer, and I have found that RAWDigger is a really good tool for investigating what is going on on the sensor. It makes for a great learning tool.

Alan

I am aware of resolution loss and quality.

I have future plans to debayer my 550d. For now I am trying to isolate data shot through a 6nm Ha filter. I don't want to blur green and blue channels with red because I have only collected red data. Red and blue only contain noise. I have been manually deleting g and b in ps and adding red to an image shot in color, but I am getting a loss in quality from interpolation. I just need the red data. I will check out raw digger as well.
This is for astrophotography btw. As mentioned earlier, it is common to use iris, pix insight also but I do not want to take on the learning curve before looking into some easy to use GUIs first. I have not had much time to mess with raw digger yet, but I will give it a go with tommorow mornings coffee

Yes that would be a very good use, and if you don't actually have any useful data in the other channels you won't really lose any resolution either. Actually I suppose that Astro at that level really falls into the specialist science and engineering sectors that I mentioned. Although RAWDigger is really good for investigating exactly what the sensor has recorded, as it has individual RAW RGGB histograms, and is also good for pulling stats from the sensor data it actually uses dcraw to do the conversions and is not really a RAW processor. I would think a GUI front end to dcraw would probably be better for this sort of thing.

Building custom kit to record from telescopes and the like sounds like a really interesting thing to get involved in, but then I am an electronics engineer by training.

Alan

If your set up is for astrophotography and you are really trying to control your extraction of data from a raw file, PixInsight or similar application is what you probably want to use.

kirk

The raw decoding library behind FastRawViewer and Raw Digger can be downloaded here:

http://www.libraw.org/​download

in the binary distribution it has several utilities that demonstrate the capabilities of the library, including one called "4channels" - here is the usage note:

4channels - LibRaw 0.15.2-Release sample. 521 cameras supported
Usage: ./4channels [-s N] [-g] [-A] [-B] [-N] raw-files....
	-s N - select Nth image in file (default=0)
	-g - use gamma correction with gamma 2.2 (not precise,use for visual inspection only)
	-A - autoscaling (by integer factor)
	-B - no black subtraction

4channels <rawfilename.CR2>