Converting negatives to positives

My advice would be to acquire an inexpensive flatbed scanner with a transparency unit. Then the scanner software will do the work . Epson’s online clearance bin has Photo scanners from $49 . Save yourself a lot of work.

:-~

Brent

If it’s a quick and dirty way you are looking for, just hit Ctrl+I (invert) to convert the negatives into positive images. As you’ve said, colour balance will be way off due to the orange mask, but you can tweek this in Photoshop to give you rough and ready reference proofs.

schrieb:

The problem is converting the scans to positives.
Using Invert in photoshop produces an image with a heavy blue cast.

Maybe, You can try this: After inverting, press Crtl+Shift+L. (I hope, this is the correct one. If not, it must be Crtl+Alt+L.) I don´t know the english word for it, but in german it is Auto-Tonwertkorrektur, which means something like automatically correcting Colour. But make sure to have no black borders, otherwise it could be, that the effect is not as good as You wanted it to be.

Kea

I would suggest what Brent suggested. I have a Plustex scanner that I bought many years ago. It still works great! It has a transparency mode in the software.

You just stick the negative in the holder and tell the utility what you’re scanning. It does the scanning and converts the image to a positive in one fell swoop.

People tell me the colors are accurate. I have a color blindness problem, so for me to tell folk how good the colors are wouldn’t be much help to anyone. 🙂

wrote in message

I am sure this has been covered before, but I can’t find anything in the

FAQs or through a search. I want to scan large format negatives, and sheets of smaller negatives, on a normal HP flatbed scanner using a reflective background, or homemade backlight. This work fine, and I get decent negative scans for my purpose, quick and dirty proof sheets for my negatives book.

The problem is converting the scans to positives. I contacted HP and other

software providers. They responded with the formula " you need a negative adapter or you can’t do it" reply. Asking if their negative adapters can scan large format negatives results in a dull silence. No thinking outside the box for those folks.

Using Invert in photoshop produces an image with a heavy blue cast. I

tried the technique shown on the Computer Darkroom web site run by Ian Lyons but his suggestions on adjusting RGB separately did not result in any change in my negative scan. I contacted Ed Hamick of VueScan but he responded that his software will not invert negatives from a reflective scan. I am at a loss. I thought this would be simple.

Does anyone have any suggestions? There should be a method in Photoshop to

convert a colour negative to a positive. Film scanners do this automatically.
So do flatbed scanners.
Jim

The problem is the ‘orange mask’ is not consistent over the whole image. It is formed in inverse proportions to the dye in two of the three layers of the negative (the cyan and magenta layers), and can only really be successfully removed at the scanning stage.

Len, where did you get that information? If so, analog printing would be a nightmare One applies the basic filter pack to correct the mask; there were published tables of the mask reduction filter for various films.

With the Epson scanner’s own software, the mask is only partially corrected (which is why many people don’t like the Epson software) and the image is bluish. Selecting a neutral gray area brings it into balance. This is global, AFAIK.

Powershute, I would try Levels, and bring first the RGB sliders to correct exposure, then open each color channel and set the end points equal, that is, each color channel should be at the edges of it’s histogram. You will be pretty close. Once you are successful, save that setting and use it as a starting point for additional scans. You will most likely have only to reset the RGB channel.

MicroTek 6100 (about 200 Euro) can scan reflective prints, positive and negative films with very high resolution (more than 2400×2400 ppi, which is already sufficient, because of grain and noise – IMO, of course ).

Even without calibration (with manual adjustments for levels and colors), the results are quite satisfying.
Scanning films is a little slow, but altogether it’s a good substitute for HP scanners, which bothered me several years by ‘warming up the lamp’.

Best regards –Gernot Hoffmann

The Epson has warm-up also. Why does it bother you?

Yeah but how do I scan a large format negative or a sheet of 2 1/4 negs? Scanners with built in transpanency adapters will only scan the adapter, usually a strip in the lid good for one 5 image strip of 35mm film. I want to do oddball sizes. If you could trick the software into converting an entire flat bed scan it would work great, but the ones I have seen will only scan the lid adapter in transparency mode, not the entire bed.

A lot of work or not, there has to be a way to create a corrective mask in Photoshop that you could then apply to a negative scan. I can’t believe this isn’t done all the time. Am I the only one in the world who scans large negatives?

Don

Ahh, didn’t see the last 3 messages before I posted. Sorry. I have tried the levels method, setting the individual colour channels to the endpoints of the histogram, but it made no difference to the image. It was still a heavy blue.

I wonder if you couldn’t "print" the negative through a corrective mask of cyan and magenta, as you do in a colour enlarger?

Don

Well, you have to measure the actual density of the mask to determine it’s value. If you have the info on the film type, the corrections to dial in will be avaialble.

If I were you, I would invest in the Epson 4900(?) and get full 8×10 neg scans.

The limitation, AFAIK, for scanning negs in earlier machines is the light source. If you are providing adequete coverage on your own, you should be able to scan 8.5×11.

You are probably too blue because you are using warm light sources. Try a blue bulb.

The problem is the ‘orange mask’ is not consistent over the whole image. It is formed in inverse proportions to the dye in two of the three layers of
the negative (the cyan and magenta layers)

Len, where did you get that information? If so, analog printing would be a nightmare One applies the basic filter pack to correct the mask; there were published tables of the mask reduction filter for various films.

The mask is indeed positive, and is there to keep analogue printing from being a nightmare. Without the mask, you would just be printing cross-processed E6 film, which, I assure you is a REAL nightmare.

So the density of the mask is less in the highlights than in the shadows? I don’t understand. In order to print consistent color, the printer would have to apply an inverse filter in density. That obviously didn’t happen in analog printing.

I have to Google this.

BTW, Agfa did produce a negative film without a mask. It was difficult, but not nightmarish.

Lawrence,

If so, analog printing would be a nightmare One applies the basic filter

pack to correct the mask;<<

On the contrary. The mask is there to compensate for dye deficiencies, and so needs to be proportional to the amount of dye present. If there were ‘perfect’ dyes there would be no need for the masking.

The filter pack is really there to correct colour balance, not to ‘correct the mask’. The mask is still doing it’s job of correcting the light transmission for the individual dye layers within the film, and an overall filtering of the entire spectrum will not effect its ability to do so.

If you want full details Langford’s Professional photography: Principles in practice ISBN 0240508432 will give it all

Would Kodak Digital ROC filter work on this? a free trial is available at: W**.asf.com

Don,

A lot of work or not, there has to be a way to create a corrective mask in Photoshop that you could then apply to a negative scan. I can’t believe this isn’t done all the time. Am I the only one in the world who scans large negatives?

I think the small minority of people who need to scan large color negatives on a regular basis have scanners that can cover the needed area. However, there are Photoshop techniques that can do what you want. The Photoshop techniques vary from fairly simple to very complicated, depending on the required quality of the conversion and the condition of the color negatives. If your color negatives are fairly old, the dyes may have degraded somewhat, and the degradation can be differential, so that the original "recipe" for the orange mask will no longer hold, and the masked negative colors themselves may have degraded.

Almost all Photoshop techniques for removing the orange mask require that you sample the pure orange mask color (sometimes referred to as "the rebate") in areas of the negative that would otherwise be black in the positive, such as near the sprocket holes in a 35mm negative. This basic orange color varies from one brand of film to another even for new films.

For a fairly simple and effective method, refer to one of Martin Evening’s Adobe Photoshop for Photographers books. I happen to have the Photoshop 5.0 edition because that was when I did some extensive work converting color negatives. At one time there were archived message threads covering that here in this forum, although they may no longer be available. This subject probably should be added to the FAQ because it does come up from time to time, and for some reason it is not generally well understood.

In his chapter on "Repairing an Image", Martin Evening presents an ingenious method for Retouching a color negative that can be readily adapted to convert it to a color positive.

If that method is insufficient for your needs, we can go into more detailed methods using Photoshop channel operations (CHOPS). To that end, it will be helpful if you can obtain a copy of the now out-of-print "Photoshop Channel CHOPS" by David Biedny, Bert Monroy, and Nathan Moody (New Riders, 1998). But don’t pay a premium price for it — I have seen exhorbitant offerings priced at several times the original list price. You might find it in a public library. As far as I know, a newer edition of that book was not released. Although it actually refers to Photoshop 4, most of the material is still applicable.

The advantage of the detailed CHOPS approach is that you can deal with variations from one brand of film to another (or from one batch to another) and you can also deal with different amounts of dye degration due to aging and such.

If you don’t want to go to that much trouble, simpler methods such as the one presented by Martin Evening can produce acceptable results.

— Burton —

Don,

This How to convert a 35mm negative into a usable digital image <http://www.photosolve.com/main/resources/pw_film_conv/> technique on the Photosolve website may be sufficient for your needs. There are, however, many Photoshop techniques for dealing with this problem. Incidentally, on the webpage I linked to, notice the reference to VueScan from Hamrick Software.

— Burton —

nevermind

Don,

Several years ago, Chuck Pink developed a Photoshop technique to Convert a color negative to a color positive in 90 seconds < http://cad.ntu-kpi.kiev.ua/%7Enetlib/graph/FOTO_negativ/neg2 pos1.html>. The website I linked to has a rather nonstandard way of navigating from page to page, but the arrows and page numbers in the upper-left margin aren’t too difficult to figure out.

— Burton —

If you want to learn about color negatives in detail, a good source is Kodak’s book Printing Color Negatives . Not sure if this is still in print, but I saw a bunch available on Amazon.