Color crossover - an illustration

koraks

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The issue of crossover pops up here from time to time, and it sometimes involves questions that boil down to "what are we looking at, exactly". Yesterday I did my best to put it into words and even pictures (scroll down from previous link to see it), but this is (1) buried rather deep inside a thread about something else and (2) I wasn't entirely happy with the visual example I worked out for it. So today I spent much of the day preparing a better explanation and example images of the crossover issue.

You will find my (amateur-perspective, hobbyist) explanation of color crossover and what it looks like on my blog, here: https://tinker.koraks.nl/photography/sickly-colors-the-crossover-issue/

In all honestly, most of the examples there are pure digital because that was the quickest and most flexible way to make a full mockup. I've also included a couple of real-world (scans from color prints) examples, but you may have seen these already on the forum because I've posted them on here before. Much of the article references to the practice of RA4 color printing and it was written with that practice in mind, but the insights expressed there are also relevant to color slides/positives and also hybrid/digital workflows.

Do with it as you please - learn from it, debate it, torched it to the ground; it's all fair game. Discussion on here is generally enriching and mostly enjoyable, so take it away, please!

(Mods, if you feel that as a result of the digital content included in the post it better fits the hybrid category, feel free to move it, but given its primary purpose of aiding people in working with film- and paper-based materials, I posted it here in the analog section.)
 
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pentaxuser

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A great idea, koraks but while I can get to your reference in you link I am unsure what the examples are that I should be looking at ? Is it the sickly colours in the flowers shot?

It may be just me but looks like I need help to get to the right article and examples

Thanks

PS Ignore the above I have found it all on an other press of the button Sorry about that

Thanks again

pentaxuser
 
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RPC

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I shoot a color chart with a gray scale on it on every roll of color film I shoot and do my own processing. If there is any crossover it will most easily show up in the gray scale, because the characteristic curves are not parallel. That is, when printing, if you balance one patch of the gray scale as gray, there will be varying degrees of color casts on the other patches, since they will not be at the same balance. If the curves are parallel, all patches will be at the same balance. A good gray scale matching the original with no shifts means no crossover. Severe enough, it is noticeable on ordinary prints. Cold temperature or diluted developing always gives crossover in my experience.
 
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koraks

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Well put, @RPC, I agree.
Towards the end of my blog I also recommend shooting a color chart at various exposure levels because it makes crossover easier to spot than a single shot. However, a single shot already goes a very long way and is usually sufficient.
 

pentaxuser

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This is a very well written article and worth studying by anyone who wants to know about crossover. Will I now recognise it more easily? Yes in some cases, maybe less so in others. I may never be as finely attuned as some in spotting it which is both a curse and a blessing

Thanks

pentaxuser
 

MattKing

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Your article is great.
Personally, I think it would be great if this thread was a Resource. Would you like me to try to figure out if it can be moved?
 

DREW WILEY

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I never get RA4 crossover issues. But back when I routinely printed on Cibachrome, a certain amount of crossover simply came with the territory. Fresh paper would lean toward green, while the highlights of six month old paper would trend magenta. I often employed this characteristic for subtle effects, either printing particular images early, middle, or late in the cycle of the paper's usefulness, according to exactly how I would or wouldn't like the highlights to bend to my will. Of course, it wasn't really a paper at all, but a polyester medium, and obviously didn't keep well.

RA4 paper keeps way better. But when it finally goes geriatric, there tends to be some overall yellowing (interesting at time), but then just overall brown smoggy smudge.

Outdated color film itself often exhibits crossover issues. So did excessively "pulled" color film.

The MacBeth Color Checker Chart is excellent for revealing exposure, printing, or processing errors. Although there is no such thing as a perfect film, in each step you want the gray scale itself to be fully neutral gray across the board, while at the same time, the row of RGB primaries and CMY secondaries should all "sing" with the same purity and intensity. Tertiary color patches, all depends. Typical color neg films struggle to differentiate similar yellows, golds, oranges, and tans, and often greens, while Ektar can struggle differentiating shades of blue.
 
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pentaxuser

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MattKing said:
Your article is great.
Personally, I think it would be great if this thread was a Resource. Would you like me to try to figure out if it can be moved?
Click to expand...

That would be helpful Matt, I have bookmarked it but it's much easier if it was available here on Photrio

pentaxuser
 

MattKing

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For clarity, I was talking about this thread being a Resource, rather than the linked to Article. It would take tools that are not clear to me to have the linked article posted directly here.
In the meantime, I'm making this thread a Sticky Thread in this sub-forum.
 

Mick Fagan

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That is a superbly written and illustrated article, congratulations.

With RA4 printing, there is one other misunderstood colour changing aspect that I see here and there. When the RA4 colour developer has been overused, or in other words, exhausted, prints tend to have blacks with a blue tinge.

Mainly the occurrence is when people are newish to RA4 printing and having some long sessions and notice the black parts of the picture have a colour change; one young printer thought she was having a colour crossover. So did I, until I saw an actual print.

The (mainly) young people taking up RA4 printing are not only working in a vacuum trying their best to get something decent, without knowing what is decent, but have until now, been unable to understand and see, within reason, what cross over is. I will be forwarding a link to them of your quite clear and informative article.
 

pentaxuser

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OK It's a pity that we cannot place an actual article as a resource. My worry as a sticky is that like Topsy it just grows to many pages and eventually becomes a real daunting prospect to pick out the really important bits

pentaxuser
 

albada

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I think this website article can be made a resource as follows:
  1. Copy all images in the article to your hard-disk.
  2. Start a new resource.
  3. Copy and paste the text. Attach images from hard-disk at the appropriate spots.
  4. Fix up minor formatting-irritations in the text.
That would be tedious, but do-able. Or am I missing something?
 

MattKing

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I would say that you are correct, and I'd be happy to assist if I can, but I wouldn't presume to decide that for koraks - it is his article!
In the meantime, I'll ask Sean and the other moderators about whether it is possible to change this thread into a Resource, and if so, how best to go about that.
I'd want to confirm that koraks is happy with that first though.
On the subject of Sticky Threads, this is now only the third such currently accessible one in this sub-forum, so uncontrolled growth isn't much of a problem.
 
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koraks

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Many, many thanks all around for the kind words, valuable additions and overall confirmation that this article might actually serve a purpose! Generally what I do on my blog is basically just a 'structured braindump' of sorts. Most of the content of my grey matter isn't all that relevant to the outside world; it's nice if there are exceptions once in a while

@MattKing and others: yes, please feel free to use this somehow as a resource. For me, it would be perfectly fine if it is stickied just as it is now. Speaking from personal experience, the stickies have always been more useful for me than the resources, for the simple reason that the stickies were easier to find for me. It somehow always takes me a trip through Google to hit upon resources, and they don't pop up all that often.
As to duplicating the content of the blog to the forum: I think that wouldn't work optimally; for one, it's kind of wordy to work as forum post, and also it would make it more difficult for me to redact it whenever errata are being pointed out to me. This does in fact happen with my blogs (already!) and I try to update/fix errors as they occur. So I'd rather keep the main piece in a place where I can still get at it to maintain it.

What I could do, is write a much briefer excerpt with just a few key illustrations, which we could add to the OP of this thread (or it could be made a resource, if you will, but as said, I think it might be more effective to keep it a sticky). This would make the central message directly accessible through the forum, and those who want to dive deeper into it can always link through to the original page. @MattKing would this be OK from your perspective?
 
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koraks

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@DREW WILEY good to see you around once again. I've never had the pleasure (or frustration??) to print Cibachrome; I was much too late to the party for this. I can attest to what you say about the deterioration of RA4 paper. It goes all canary once it goes bad. Most of it appears to be a simple shift mostly on the yellow/blue axis and to a much lesser extent magenta/green, although Endura and Crystal Archive papers seem to differ in exactly this aspect, with Endura shifting almost equally as badly to green as it does to yellow. I'm not sure if old RA4 paper crosses over so much, but the shift gets so bad at a point that it becomes hard to tell.

@Mick Fagan yes, that's an excellent addition on the blue blacks with overused or otherwise old & tired RA4 developer. It is indeed a form of crossover and no amount of filtering will evidently get one out of that particular hole. Perhaps a useful addition as well would be that while still wet, the color balance of RA4 paper is distinctly different from the dried print, and this effect is the stronger as density is higher. So technically, it can be regarded as a very temporary and unharmful form of crossover. Much like expired developer, the blacks on a wet print tend to be blue, but there's also an overall saturation increase that occurs on drying. With Crystal Archive I find that in particular the magenta + yellow dyes somehow standing out more in the dried print as opposed to the wet one. If I print something with a lot of red in it, I can really see the red 'develop' as the print dries.
 

Alan Johnson

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I am not too happy to see my pictures linked in this thread.
IMO elimination of all crossover merely produces a technically perfect result like billions of others that could have been taken with any half decent phone.
In my view it is preferable that pictures taken on film should not look like digital.
 
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koraks

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Alan Johnson said:
I am not too happy to see my pictures linked in this thread.
Click to expand...

It's not being done, is it? I avoided it in any case; they're your images, not mine to use.

Alan Johnson said:
In my view it is preferable that pictures taken on film should not look like digital.
Click to expand...

Crossover is not a necessity for this. I respect your opinion, but mine is different. A film-based image should be capable of being free of any crossover. If one chooses to add this for artistic effect, that's another matter. Inherently curtailing a process to limit it to a crossed-over look is something I would never strive for.
 

warden

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I thoroughly enjoyed reading this, koraks, thanks!
 

warden

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koraks said:
Thanks @warden, much appreciated!
Click to expand...
I have some old C41 scans that I have been unsatisfied with and your blog post has encouraged me to dig them out and adjust individual channels to see if I can identify the crossover issue. I recall having the most difficulty with Ektar, which would deliver something close to perfect in some images while others would be obviously wrong and difficult to correct.

I have quite poor color vision so that's not helping matters, which is why 99% of the time I stick to black and white. I remember sharing color pictures of my kids once online and a relative told me that I was using an interesting color effect on the images. When I asked them what they meant they said, "the green skin, of course!" A quick check with the eyedropper confirmed that my sons were in fact martians. I had no idea.
 
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koraks

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Ektar is a tricky film - that is to say, any material that has high saturation will pretty ruthlessly punish any error, however small. A slight filtering mishap that might not be very conspicuous on say Portra 400 can become a glaring issue on Ektar. T
Truth be told, I never enjoyed color correcting C41 scans...I found it a frustrating business, overall!

warden said:
my sons were in fact martians
Click to expand...


I hope they're OK now
 
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