*ist D raw files


Link Posted 23/08/2004 - 01:30
I've had my *istD now for about 10 months and had never really seen the point of using RAW because the Pentax software is so slow and limited in function. I've recently upgraded to photoshop CS and downloaded the Adobe RAW plug-in. I now realise why it is better to use RAW. The results I am getting are better than I would have hoped for and if I get the exposure a little wrong I can correct it from within photoshop without losing detail as so often happens when working in jpeg.

I have noticed that the exif in the photoshop browser appears to say that in RAW format the information is recorded at 16 bit per channel. Does anybody know if this is true or is it a mistake in the software. I had been under the impression that the camera recorded at 8 bits per channel whether jpeg, tiff or RAW and that the option in Pentax photo lab to save at 16 bit per channel created bigger files with no more information in them.

I am confused and I probably haven't put this very well. I suppose the question is. Does the Pentax *ist D record at 16 bits per channel in RAW format? I'd love to know. If anyone can clarify I would be most grateful



Link Posted 23/08/2004 - 09:33
The format actually records 16-bits per pixel. However, that doesn't mean to say there are 16-bits of information

The RAW format is 12-bits per pixel (I believe), with the extra four bits packed out with zeroes. This allows for future expansion where a CCD is clean enough to produce more than 12. (ie a smaller step between each level of light).

JPG is always 8-bits per pixel (only JPG2000 can support more), and so the *ist-D throws away some information when converting internally from RAW to JPG.

The extra 4-bits of data in each pixel are the reason why you can push/pull the RAW format without losing too much detail

Hope that explains things!

(For gallery, tips and links)


Link Posted 23/08/2004 - 21:24
Thanks for clearing that up Matt. It's useful to know.
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