dlRaw: hotpixel reduction

Posted Sat, 07/11/2009 - 02:21 by mike

Hi folks,

just a short update, to let you know, that work is still preceding... You probably noticed my last pictures on the blog. They are pretty clean as you see them there, but while processing them I had a problem with hotpixels. My old and trusty Pentax K100D has some bad pixels when used with higher ISO. Although it's not so bad on the pure picture, when sharpening the image bad pixels like to shine out Sad So I had to remove these small blemishes on all of them manually in gimp afterwards... Of course I didn't like that Wink During the week I tried to code an algorithm removing them; finally today I can report first results.

The algorithm works at the moment only on 1:2 and 1:4 images, because on 1:1 pipe it is better to work on the Bayer pattern directly and that is still work in progress... But on 1:2 I'm pretty satisfied with the result. The two attached images are both way oversharpened, that is just to show you how many bad pixels there are. Usually, with normal sharpening, one would only see a view of them, but those would still be distracting. The difference between the two pictures is just the hotpixel reduction nothing more.

So stay tuned for more news about dlRaw Wink

greets mike

Comments

How to use "Bad Pixels" file?

by Serguei (not verified) - 29/06/2010 - 12:06

Hello, I have successfully compiled dlRaw on Fedora 12, with a few patches though... Thank you for such a great program. I'm playing with it now. Using a simple palette.png I have found a channel mixer matrix which produces better results than supplied with dlRaw ICC profile for my Canon A610. It's really nice application.

Now I'm trying to figure out how to build and use "Bad pixels" file. I tried to build a dcraw compatible badpixels but when I load it using "Load one" choice, nothing happens.

Any idea?

Thank you and best regards,
Serguei.

Hi Serguei, I haven't used

by mike - 29/06/2010 - 20:14

Hi Serguei,
I haven't used that feature up to now, since I was to lazy to map each single one. The implementation of that feature is also not my work, this was done by Jos, while he was actively working on dlRaw. So, I'm most likely not the perfect person to ask ;-) However, after a short glimpse into that part of the code, it should be working with files of that format, sample by Dave Coffin. However, you will see the effect only when working on the 1:1 pipe, or after using the full output option (which runs the 1:1 pipe).
I hope this helps.

greets mike

Thank you for your reply.

by Serguei (not verified) - 30/06/2010 - 06:06

Thank you for your reply. While I was waiting for it, I checked the code and then edited dlRaw.ini file manually changing related lines to

BadPixels=2
HaveBadPixels=2
BadPixelsFileName=full_path_to_dcraw_compatible_badpixels_file

After that it started to work.

Thank you Serguei, I'll check

by mike - 01/07/2010 - 10:21

Thank you Serguei,
I'll check the internals for this.
greets mike

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