CHDK Canon RAW hack in action (Big post)

[String]

(Repost as original vanished)

Took the Canon A620 to NDAC on Sunday to test the new RAW function provided by the hack.

All photos other than the fish, zimmer and reel taken at a depth of 26m and visibility no more than 3m - LOTS of silt and algae and very dark. All done on ambient light (no strobe or internal flash)

All taken with 1/40th shutter and white balance set to cloudy. There was no calibration done in the water.

All the after shots are nothing more than the adobe camera RAW (v4) functions for white balance, fill light and so on and are compared to the original JPGs off the camera. No other fancy post processing and each one took about 30 seconds to do.











In short thanks to the power of being able to edit the RAW files offering way way more flexibility than the old JPGs i can lock a shutter speed to avoid blur and correct any underexposure fairly well in software. In addition i don't need to recalibrate white balance every 2-3m or so with a slate thus making it far less time consuming.

I tried the same edits with ACR on the JPGs produced instead of the raw files and couldnt get anything like the same results.

The hack has given my camera a new lease of life - if you have a canon DIGIC-II or III compact then its really worth getting this (free) software.

[John63]

Incredible difference.

What is the hack / where did you get it from. I have a Canon A640 and would like to give this a try.

Cheers, John

[Bardo]

It's worth noting that you can get similar results simply by using manual white balance. That said, being able to manipulate a RAW image offers considerably more flexibility... just wish my IXUS 75 was on the list of supported cameras. Sore? Moi?

[copperband]

Originally Posted by Bardo

It's worth noting that you can get similar results simply by using manual white balance. That said, being able to manipulate a RAW image offers considerably more flexibility... just wish my IXUS 75 was on the list of supported cameras. Sore? Moi?

You can still do a lot of colour correction with a jpeg Bardo, please don't cry.

[Bardo]

Originally Posted by copperband

You can still do a lot of colour correction with a jpeg Bardo, please don't cry.

Well aware of that mate. Trust me - I discovered the joys of Adobe Lightroom a long time ago and definately wouldn't be without it now. I'd say that it's probably even more useful than Photoshop for photo colour correction.

Whilst I'd agree that you can do a lot of colour correction with a JPEG, there is a limit - after all, if the colour information isn't there then it's not there. It's as simple as that. I find that the best thing to do is to either use an external strobe or use manual white balance to give Lightroom a fighting chance of getting as much accurate colour information out of an image as it can.

You're right though - Lightroom is an absolute godsend to digital underwater photographers. If you take photos underwater and you're not using Lightroom then you definately don't know what you're missing...

[String]

Manual white balance has the annoying need to recalibrate when you change depth or lighting which can sometimes be inconvenient depending on the dive.

You can pull a lot more in the way of highlights out of the RAW than JPGs and other things aren't lost in compression or the cameras sharpening. Some are better than others in their rendering of jpgs but at the end of the day there is more scope for rescue and alteration from a RAW image. Also useful is to increase exposure from an underexposed shot which i tend to do a lot underwater due to locking a shutter speed and not owning a strobe. JPG seems fairly bad at that.

The hack can be found here:
CHDK - CHDK Wiki

As well as RAW it introduces other features like custom iso, shutter speeds, f-stops, increase flash sync speed and a lot more features generally only found (or unlocked) on more expensive.

[David P]

Originally Posted by String

Manual white balance has the annoying need to recalibrate when you change depth or lighting which can sometimes be inconvenient depending on the dive.

Accept that - BUT if you're "about right" in the first place, then the resulting correction, fine tuning or polishing (particularly on a JPEG) becomes MUCH easier and more successful.

(Yeah, I'd prefer RAW as well - but so be it, the F30 will do for now...)

[copperband]

Originally Posted by Bardo

Well aware of that mate. Trust me - I discovered the joys of Adobe Lightroom a long time ago and definately wouldn't be without it now. I'd say that it's probably even more useful than Photoshop for photo colour correction.

Whilst I'd agree that you can do a lot of colour correction with a JPEG, there is a limit - after all, if the colour information isn't there then it's not there. It's as simple as that. I find that the best thing to do is to either use an external strobe or use manual white balance to give Lightroom a fighting chance of getting as much accurate colour information out of an image as it can.

You're right though - Lightroom is an absolute godsend to digital underwater photographers. If you take photos underwater and you're not using Lightroom then you definitely don't know what you're missing...

Agree with everything you say, and it wasn't an advert for Lightroom really, I took that screenshot as it said before and after on it and I couldn't be arsed posting both shots next to each other, plus it showed that you cannot correct the colour any more with the dropper tool as it is at 100 thus showing RAW to be superior in that all information recorded at the time the shot was taken is there for us to mess with, not what the camera thinks we might need . Although other options are still available in Lightroom for colour manipulation.

Plus, I didn't want to see you cry

Great pics though and good example the hack worked.

[Bardo]

Originally Posted by copperband

Agree with everything you say, and it wasn't an advert for Lightroom really, I took that screenshot as it said before and after on it and I couldn't be arsed posting both shots next to each other, plus it showed that you cannot correct the colour any more with the dropper tool as it is at 100 thus showing RAW to be superior in that all information recorded at the time the shot was taken is there for us to mess with, not what the camera thinks we might need . Although other options are still available in Lightroom for colour manipulation.

Plus, I didn't want to see you cry

Great pics though and good example the hack worked.

Hehe. Agreed - just wish the hack was available for my IXUS 75 so that I could shoot in RAW.

My next camera definately has to have full manual control *and* RAW support - I just wish Canon would hurry up and bring out their fabled compacts with CMOS sensors and full manual control...

[johnoh]

Checking the forums, they are working on it now...

IXUS75/SD750 1.01a (Finished) | 1.00b (Porting) | 1.02a (Porting)

I've not got a 75 but there is a version to download and try, depends on ur version of camera... worth trying?