Powershot A720 raw colors

pshotuser

27

Powershot A720 raw colors

« on: 24 / March / 2012, 08:12:12 »

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Hello everyone,

i'm new to this forum and i would like to say thank you to all chdk developers.

I have 2 powershots, an A640 and an A720.

I have installed chdk on both, and while on the 640 i get "right" colors on the fly when processing raw files (converted directly with raw therapee or converted to dng via dng2ps2 and after processed always with raw therapee), with the a720 i get really weird colors in both ways, colors are really off (and thus files are, for me, really difficult to manipulate and convert back to jpeg)

I have seen there is a procedure to calibrate colors, i have tried to shoot an image as described here:
http://chdk.setepontos.com/index.php?topic=390.0

The raw file and the jpg one are on zshare:

Calibrazione720.7z - 8.43MB

But with dng4ps2 i have been unable to calculate it (the program crashes).

Still i don't know, maybe it is a raw therapee problem.

There's also another question and i haven't found an answer in the faq...

I have seen there is a way to save directly in dng. What are pro and cons of using dng instead of "crw"?

For sure dng is more portable, but in terms of quality are they the same or i'll loose some data?

Thank you in advance.

« Last Edit: 12 / May / 2012, 15:17:28 by pshotuser »

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waterwingz

12139

Re: Powershot A720 raw colors

« Reply #1 on: 24 / March / 2012, 10:43:49 »

Quote from: pshotuser on 24 / March / 2012, 08:12:12

I have installed chdk on both, and while on the 640 i get "right" colors on the fly when processing raw files (converted directly with raw therapee or converted to dng via dng2ps2 and after processed always with raw therapee), with the a720 i get really weird colors in both ways, colors are really off (and thus files are, for me, really difficult to manipulate and convert back to jpeg)

If you create a DNG on the a720 using CHDK (not just convert it from RAW afterwards) how do the colors look ?

Quote

I have seen there is a way to save directly in dng. What are pro and cons of using dng instead of "crw"?
For sure dng is more portable, but in terms of quality are they the same or i'll loose some data?

DNG takes a little longer to save after each shot as the camera has to do extra manipulation. And it takes a bit of work to setup ahead of time - you need to create a badpixel.bin file with a CHDK menu option. Otherwise its a better choice as it is a lot more portable across PC apps. And there is no sacrifice in quality or resolution - DNG and CHDK RAW hold the same image information.

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Ported : A1200 SD940 G10 Powershot N G16

pshotuser

27

Re: Powershot A720 raw colors

« Reply #2 on: 24 / March / 2012, 15:21:31 »

Quote from: waterwingz on 24 / March / 2012, 10:43:49

Quote from: pshotuser on 24 / March / 2012, 08:12:12
I have installed chdk on both, and while on the 640 i get "right" colors on the fly when processing raw files (converted directly with raw therapee or converted to dng via dng2ps2 and after processed always with raw therapee), with the a720 i get really weird colors in both ways, colors are really off (and thus files are, for me, really difficult to manipulate and convert back to jpeg)
If you create a DNG on the a720 using CHDK (not just convert it from RAW afterwards) how do the colors look ?

I have created badbixel.bin, tomorrow with some light i'll try. Thank you.

Quote

Quote
I have seen there is a way to save directly in dng. What are pro and cons of using dng instead of "crw"?
For sure dng is more portable, but in terms of quality are they the same or i'll loose some data?
DNG takes a little longer to save after each shot as the camera has to do extra manipulation. And it takes a bit of work to setup ahead of time - you need to create a badpixel.bin file with a CHDK menu option. Otherwise its a better choice as it is a lot more portable across PC apps. And there is no sacrifice in quality or resolution - DNG and CHDK RAW hold the same image information.

Thank you again, good to know. Are there time comparisons? (both cameras are already quite slow by themselves, and saving raw certainly doesn't help)

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waterwingz

12139

Re: Powershot A720 raw colors

« Reply #3 on: 24 / March / 2012, 15:25:49 »

Quote from: pshotuser on 24 / March / 2012, 15:21:31

Thank you again, good to know. Are there time comparisons? (both cameras are already quite slow by themselves, and saving raw certainly doesn't help)

Saving DNG instead of RAW has been reported to take up to a second longer per image.

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Ported : A1200 SD940 G10 Powershot N G16

pshotuser

27

Re: Powershot A720 raw colors

« Reply #4 on: 25 / March / 2012, 06:23:57 »

Quote from: waterwingz on 24 / March / 2012, 15:25:49

Quote from: pshotuser on 24 / March / 2012, 15:21:31
Thank you again, good to know. Are there time comparisons? (both cameras are already quite slow by themselves, and saving raw certainly doesn't help)
Saving DNG instead of RAW has been reported to take up to a second longer per image.

Ok thank you.

I have tried using dng right on the camera: color are somewhat better than "crw", but still there is a strong color cast.

Here is a link with a crw, a dng and its jpg.

Dng-Crw-Jpg-A720.7z - 14.72MB

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waterwingz

12139

Re: Powershot A720 raw colors

« Reply #5 on: 25 / March / 2012, 09:56:30 »

Quote from: pshotuser on 25 / March / 2012, 06:23:57

Here is a link with a crw, a dng and its jpg.
Dng-Crw-Jpg-A720.7z - 14.72MB

I know it sounds petty, but I don't download anything from zShare. Its an ambush site that makes it hard to see what needs to be clicked for the actual download - the big icons on the page download swill and crapware rather than what you requested. To add insult to injury, they make you wait 45 seconds after navigating through the above mentioned mess before the download will start.

No thank you - I'll take www.box.com any day.

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Ported : A1200 SD940 G10 Powershot N G16

pshotuser

27

Re: Powershot A720 raw colors

« Reply #6 on: 25 / March / 2012, 13:42:37 »

Sorry for zshare (never used before, i have used it because it was suggested @ http://chdk.setepontos.com/index.php?topic=390.0 )

Try here:
http://ubuntuone.com/2DIJrpN8lrick4NSZgpdSC

Thank you.

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waterwingz

12139

Re: Powershot A720 raw colors

« Reply #7 on: 25 / March / 2012, 15:23:51 »

Quote from: pshotuser on 25 / March / 2012, 13:42:37

Try here:
http://ubuntuone.com/2DIJrpN8lrick4NSZgpdSC

Sweet ! Even better than box.com. Just downloads when I click on it - no intermediate stuff required !

So, on my laptop (with its limited screen - its not a "new" fruitPad with a retina display) the two pictures look pretty darn close. Enough so that I'd say that CHDK on the camera is working perfectly. This is what the sensor "sees" - the jpeg has Canon's corrections applied. You can probably get different corrections if you change the shooting mode on the camera by the way. So what you have now is a "perfect" version of what the sensor sees - its up to you to correct it to your taste on your PC. People seem to feel that RAW images will be perfect and that Canon is somehow evil by not letting you have them. The fact is that someone has to correct the raw sensor image - you or Canon when they make a jpg.

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Ported : A1200 SD940 G10 Powershot N G16

pshotuser

27

Re: Powershot A720 raw colors

« Reply #8 on: 27 / March / 2012, 12:06:18 »

Ok, thank you.

Still seems strange to me that the a640 one looks already nearly perfect.

By the way, what software have you used?

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pshotuser

27

Re: Powershot A720 raw colors

« Reply #9 on: 14 / April / 2012, 13:48:00 »

I have tried more and dng's are not bad at all.

Is there a way to convert crws (i have many of them) to dng in order to obtain a result that is similar-equal to the dng produced in camera? (dng4ps2 doesn't seem to work, colors are still as off as with direct crw).

Thank you in advance.

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