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View Full Version : Solution to Red/Magenta Shift problem with G1


Geza
27th of February 2002 (Wed), 19:28
(this posting is also a reply within another message thread "What kind and strenght of filter would you use with this problem? "
but I thought, I'd post this one here with a new and meaningful title in case someone has the same problem and looking for a possible solution.)

Well,
Here you can see the result of my test shots:
http://www.lhaarchitects.com/g1/020227_Red_Mustang/

As you can see, the Red Mustang turned magenta when the camera was set to JPG format, but no sign of magenta when my G1 is set to RAW.

I've been reading and researching about this subject in the past few months on CANON user forums, and red zillion messages about all sorts of terms attached to the words "purple" and "magenta": like "fringing", "casting", "shifting" and these messages confused me a lot about possible solution to my problem of "red/magenta shift".

Although I have noticed fringing and casting too on some of my images, they must've not bothered me enough to do something about it, at least not as much as the red/magenta shift-problem.

Finally, I do have a solution to my problem
and the proof for that the quality of JPG image processing in the CANON POWERSHOT G1 is Waaay below the standard that someone or I would expect(ed) from CANON when I decided to purchase one.

I called CANON technical support and Customer Relations Dept. several times in the past they had my camera two times since last September, and they just couldn't tell me (or figure out), that if I want the red/magenta shift problem go away, I have to switch to RAW mode.

Since I will take pictures only in RAW mode in the future, I will have to invest in another CF card because my current 128MB Lexar one can only hold 49 RAW images, plus an extra battery, because I will discontinue taking shots by using the viewfinder so that I can do -EV or manual corrections based on the LCD display.

Geza

Leighow
27th of February 2002 (Wed), 21:56
GEZA

You seem to be right . RED Mustangs are is RED in your raw photo. I have yet to use raw (only 32 Meg ).

However, I wanted to mention that I was pleased with the ease with which I could adjust hues in PS. While I have used this PS feature in the past on sannned summer photos, it seemed hardly worth the effort. In contrast, it was the perfect solution for correcting the "bluish" shadows and snow that flawed some snow scenes that I took last weekend.

I will try RAW and it sounds like a bigger card will be a neccisity.

HOWIE

Harv
28th of February 2002 (Thu), 11:58
Yeah, I don't think anything can be done about the magenta fringing, I don't notice it in prints though so I've never worried much about it.

Be sure to check B&H photo for CF cards. They're a great house with good prices.

I initially used a 340 Micro Drive until I dropped it from a height of about 9 inches and it died. I'll never make that mistake again.

I now use the Jumpshot CF cards which are very nice, much faster all around and with far greater durability. Reviewing in camera is at least twice as fast.

I got the 12X 256MB cards from B&H for $140 each. Not a bad deal. If you get a jumpshot card consider getting the jumpshot reader, which is often bundled with the CF card, downloads will speed up a LOT. They download at normal speed or maybe even a bit slower than a regular CF card in a standard Zio reader.

www.bhphotovideo.com

Mike K
28th of February 2002 (Thu), 14:52
about Aug-Sept last year there were as series of posts on DPReview CTF by Nahau which showed how the magenta cast in G-1 JPEGs could be easily resolved by shooting RAW then converting. Whith the change in sensor filter in the G2 this is no longer an issue.

Good buys are avaialble for the 256 mb size CF, which I consider the minimum for the G-1/2. If price is a real priority, the $83 of Mr Flash is among the cheapest, but it is slower on downloads.
http://www.newegg.com/app/ViewProduct.asp
if you want something faster, the Ridata are well liked and are moderately priced:
http://www.powerinnumbers.com.au/ridata/
Mike K

teekay
1st of March 2002 (Fri), 19:37
Thank you GEZA - now I'm not tempted to buy a G2!

I have just made some test shots comparing RAW and JPG and there is no question that the G1 gives an overall magenta hue to JPG shots.

Take a look at a comparison in the composite I have put on a temporary page at:

http://www.netidea.com/~teekay/temp/rawtifcomp.jpg

Converting a RAW to JPG in PSP does not introduce this magenta effect so you have to wonder why Canon did this in the camera.

Geza
1st of March 2002 (Fri), 20:48
Hi teekay,

If I am not mistaken, the G2 has this very specific problem corrected, both optically and image processing-wise.
I have not seen a proof of this though.

I wish I'd had the extra money for a G2 now, it just doesn't seem racional to me to sell my G1 for $300 (bought it for $800 about a year ago) and spend an extra $400 just to have a G2. I will wait at least another Gx generation and get that one maybe.

I also have a Canon EOS A2 with 2 great lenses, I am waiting for the digital EOS SLR bodies to go below $1000, then I will get one of those.

About the G2, based on lots of reading of user feedbacks, the main problem is in the unreliable focusing system similar to G1. You just can not simply rely on it when you mean business. But for hobby? Why not?

It's s puzzle for me how can CANON with all the excellent records with SLRs has skin on their faces to caugh up such a lousy focusing system.
Couple years ago if some one would've spoken of Canon like I do now, I'd considered him a lunatic. Not anymore.

It looks like Canon's main marketing target for the year 2000 and 2001 was the mass market, (mass of people who don't care about quality and has no big bucks for digital SLRs)

And if you plan to rely on technical support when you have problem with your digital camera, don't consider buying a CANON digital camera. Their technical support deptartment has nothing to do with
-digital photography,
-contact with Canon's own R&D department, (this shows in their knowledge of their own products)
-interest in making their customers satisfied and happy,
- and honesty, when it comes to admitting a flaw in their own product.

Geza

Leighow
1st of March 2002 (Fri), 21:49
GUYS

My instincts tell me that with a slight adjustment to HUE and SATURATION (re the mountain scene composites) in Adobe would cure the JPEG's slight tint. But I accept that the Mustang "looks" like a tougher fix in JPEG.

HOWIE

teekay
2nd of March 2002 (Sat), 12:08
Leighow wrote:
GUYS

My instincts tell me that with a slight adjustment to HUE and SATURATION (re the mountain scene composites) in Adobe would cure the JPEG's slight tint...

Agreed, but I had got fed up with doing that to almost every image.

Harv
5th of March 2002 (Tue), 16:43
Check out dpreview.com and look for the info on the new Foveon chip that's out.

This ought to make some big waves in the digital camera world. Personally, I'm figuring on holding onto my G1 with the hopes that Canon adopts the Foveon chip and uses it in the next camera.

The G2 was never a big enough step up to warrant selling a G1 for.