k5 vertical band in raw

Started Apr 19, 2011 | Discussions thread
GordonBGood Veteran Member • Posts: 6,312
Re: k5 vertical band in raw

Pontiac Paulie wrote:

Thanks for the help folks, it was Picassa, If I use Silky Pics everyting is alright.

Paul, perhaps I can add a little enlightenment to what causes the strange vertical strip on the right side of raw images from many Pentax DSLR's (in landscape orientation) for many raw converter programs, including Picasa, as follows:

1) Many or most of the free raw converter programs are based on the open source raw converter written in the computing language 'C' from Dave Coffin, or dcraw. This inclusion may be limited to only the routines used to read and decompress the raw data and meta data as required with custom actual raw Bayer Colour Filter Array (CFA) pattern interpolation or "demosiacing" or may include all of those routines as used by dcraw.

2) Most Pentax camera raw data files include a margin of "garbage" strange photosites on the right side which are included for no known reason other than perhaps it is the way the hardware graphics engine scans the sensor.

3) There is meta in the Pentax raw files which identify the actual area of the sensor exposed to light so that raw conversion programs can strip the extra border areas from the image.

4) A programmer can read the dcraw source code to see that it does not fully read and/or does not properly apply this meta data border information to properly crop the Pentax DSLR raw images.

5) This extra strange vertical band (for landscape orientation images) is present for many of the free image viewers/converters, such as Picasa, Faststone, RawTherapee (at least for older versions), etcetera.

6) The presence of these strange borders is not really an indication of a poor conversion as they do not affect the rest of the image and may be simply cropped out if one generally likes the rest of the results.

Regards, GordonBGood

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