I'm a little puzzled by the R3/3000 description. While I haven't used Kodak chemistry, there was NO "reversal exposure" with either PhotoColor or Tetenal.
Originally Posted by b.e.wilson
There is a special type of Color film - "Internegative" - made without the "dark yellow" bias. Copying onto that, and then printing, will result in *very good* color fidelity. The "best" commercial labs will use this stuff... the others - who knows? - apparently out-dated Kodak Gold, from what I've seen.
Ed Sukach, FFP.
It seems to be down. Sods Law - it was working fine when I posted the link this am. You can find it on goole with: wendy carlos retinex, but that link is down too.
Originally Posted by Ed Sukach
There are other retinex pages, but Wendy's are particularly good.
Bazzarely, retinex theory (discovered By Edwin Land of Polarioid fame) sugguests that in a situation like the sky image posted above, where the sky is predominantly red, is exactly the situation when you'd swear there wasn't any red to be seen!
Let's look in another direction. How about your monitor? Is it calibrated properly? There are instructions with most monitors that show you how to do that.
Is your scanner calibrated? If you have a "sheila" negative or print (That's a perfectly color corrected negative/print) you could scan ithat "perfect color" image and see if the "perfect color" shows up on your (calibrated) monitor. If it doesn't, then you should be able to adjust your scanner so that your calibrated negative/print matches the view on your screen.
All the other posters above have valid points. But, you also have the complication of scanning and monitor performance to complicate this color business.
That's why I stick with black and white
Again, my ignorance is showing, but I don't at all get the retinex stuff. What I did read dealt primarily with color blindness and how colors are affected by sodium and blue light. I didn't read anything that formed a connection for me between looking at a blue sky and ending up with a red sky in print.
I'm also lost on the whole callibration deal. If scans of my prints look like the actual prints then it seems reasonable to me to assume that the negatives are scanning relatively true.
I know that when I view a "scale" from black to white on my monitor I can see the full range from white to black. And I repeat, my print scans match the prints. If you're saying that I'm not really seeing what I think I'm seeing, that the image and the scan do not really match then it's all moot. In which case I'm sorry to have wasted everyone's time.
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Retinex is an example of how the colours we perceive, are not the same colours as we're actually experiencing. Hopefully the site is back. The following image is composed of only red and white: http://www.wendycarlos.com/colorvis/gridbig.gif
There is NO green or blue - load it into photoshop, and check with the dropper tool!
re calibration - if your scans look OK on screen, then they're OK on screen. On the other hand there's no reason to assume they'l look OK when you print them, or send them to someone else. There are (at least) three problems reguarding calibration. First off we have the (false) notion of red, green and blue. Let's skip past the problems of three colour representation, and then ask WHICH three colours? "red" is a pretty vaugue concept. sRGB (a standard for computer monitors) defines the colour of "red" on a monitor. Thats not the same as the red sensor in your camera or scanner. Your printer doesn't even have a red cartridge - it has CMY and K. All of these colours are defined in terms of cieXYZ which are a set of "standard" primary colours. If you know what your red channel represents in terms of cieXYZ you can map it to any other set of primaries.
However we still have the problem of the relative intensity of the three channels. White is defined as "equal" amounts of (say) RGB. Unfortunatly our eyes will accept just about anything as "equal" - thats why we can call daylight "white" and a lightbulb "white", even though they're actually very different colours. Again there are standards defining "white" as a cieXYZ colour mix. Your monitor probably has a "color temperature" setting, allowing you to select things like 5900K and 9000K. These are the differences between tungsten lighting and daylight - try chainging it: your images will look radically different, yet they're all just as "right". The different temptratures on a monitor look very "wrong" for about 30 seconds, then your eyes adjust, and they all look very similar. The idea of white also mixes with the idea of Gamut - monitors,printers, photographic paper, slides etc all have a physical limit on the colours they can represent. This can throw the colour balance off.
Finally there's gamma. you would think that a pixel value of 1 would be twice as bright as one of value 0.5. This is only true in a linear colour space. Most digital image files are stored in a logarythmic format, which hopefully matches your monitor's logarythmic response. There are LOTS of reasons to store images in a linear format, but it's rarely done. You can however measure the gamma of your monitor, and adjust your images so they display correctly on it (for example the machine I'm on at the momment has a gamma of 3 - rediculously high, so all images are VERY dark).
Sorry if this drifted into slightly digital territory - the principles are all actually analouge, and I'd guess most people who print colour, encounter this stuff. It's imply the for most of us the guy down the lab deals with it all (or not). Part of scanning, and printing colour at home is that you bring home all the problems...
(colour is one of my pet rants...)
Scanning a color neg is a totally different ball game than scanning a print. In the analog process you have to use different filter settings for different brands of paper AND different brands of film. Then on top of that there are the various corrections applied for the "errors" in lighting the scene in the first place. The scanner has an automatic exposure and color balance routine, which in most cases you can influence at the time of the scan, for both reflection and transmission copy. Also the scanner has a different light source for each and needs its own tweaking between the two. So you can have prints looking fine and negs be off or vice versa if the calibration is off. Add to that the fact that you really don't know what the colors of the negative is before you scan it, unlike a print, simply because its negative color.
Looking at the rainbow shot, I'd say the lab messed up the color and you got the scan right but the tree looks good on the print and the scan looks too red assuming the bark is supposed to be grey.
Bottom line is you have to be the judge as to whether the color is right, you shot the picture.
I still don't understand some things but I do appreciate all the input - even if I'm still confused by some of it. I'll have to explore and give some of the suggestions more thought.
Thank you all very much.
There is green and blue when I load it into photoshop. And, yes I measured it with the dropper zoomed in.
Originally Posted by 127
At least one of the photo-processors round here (Jessops) offer a manual individual inspection and adjustment during the printing process. It costs an extra £1. On the rare occasions I shoot C41 I generally go for it. Bear in mind though that the "inspection and adjustment" usually takes about a second per frame, and I've still had pretty ropey results...
A few years ago I shot a sunset at Morecambe Bay. I had a roll of Fuji Reala in the camera, so I finished that off and then reloaded with Velvia. The Reala came back first and I was gutted. They weren't even indifferent. They were just plain awful! Then the Velvia came back containing some of the best shots I've ever taken. (I know Velvia is super-saturated and Reala isn't, but that wasn't nearly enough to account for the difference!)
Like I said earlier, I don't shoot much C41 any more...