Luminous Landscape Forum

Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: madmanchan on February 16, 2012, 02:26:50 pm

Title: Free software tool to fix CCD defective pixels/columns/rows, etc.
Post by: madmanchan on February 16, 2012, 02:26:50 pm

Hi all,

Some users have written to me about a rare problem they've experienced with their cameras (with CCD sensors). Due to the way CCD readout works, a defective pixel can sometimes turn into a defective column or partial column (e.g., vertical line artifacts in the image).

The solution is to send in the camera (or at least supply a sample image to the vendor) so that the vendor can update the firmware, which maps out the defective pixel for future images. However, that doesn't help with your existing images -- i.e., images you've already shot. Those existing images will still have the artifact since it is in the recorded image data.

So, I have now written a free software utility (Mac only for now) to fix this problem.

Here's some informal documentation (overview, limitations, instructions, examples, etc.):

http://people.csail.mit.edu/ericchan/tmp/FixBadPixels.pdf

And here's the software package, in case you want to give it a try:

http://people.csail.mit.edu/ericchan/tmp/FixBadPixels.zip

Eric

Title: Re: Free software tool to fix CCD defective pixels/columns/rows, etc.
Post by: EricWHiss on February 17, 2012, 02:24:50 am

Eric,
I didn't write to you about this problem but definitely had it with one of my Leaf backs for several hundred otherwise wonderful files.   I'll be giving this a try.  Many thanks for making it available!
Eric

Title: Re: Free software tool to fix CCD defective pixels/columns/rows, etc.
Post by: hjulenissen on February 17, 2012, 03:30:29 am

Really neat that you can do this by supplying metadata to the raw developer instead of touching the raw data yourself.

Can this be used for other things as well? non-uniform gain, variable noise, etc?

-h

Title: Re: Free software tool to fix CCD defective pixels/columns/rows, etc.
Post by: greygrad on February 17, 2012, 10:17:28 am

Nice one Eric - much appreciated.

Title: Re: Free software tool to fix CCD defective pixels/columns/rows, etc.
Post by: ondebanks on February 17, 2012, 10:43:29 am

Even though I can't use a Mac app right now, I still have to say - Eric, you da [Mad]man!

Ray

Title: Re: Free software tool to fix CCD defective pixels/columns/rows, etc.
Post by: eronald on February 17, 2012, 03:09:21 pm

Cute. Thx.

Edmund

Title: Re: Free software tool to fix CCD defective pixels/columns/rows, etc.
Post by: ced on February 18, 2012, 07:01:30 am

madmanchan that is a nice gesture to the photo community, thanks for taking the trouble!

Title: Re: Free software tool to fix CCD defective pixels/columns/rows, etc.
Post by: Dustbak on February 18, 2012, 10:38:33 am

Having had this problem (and send in my back to fix it), I know how annoying this can be. Many thanks for your very kind gesture of supplying a tool to fix this.

Title: Re: Free software tool to fix CCD defective pixels/columns/rows, etc.
Post by: Graham Mitchell on February 19, 2012, 03:12:41 am

Nice one. I hope I never need it :)