Scanning a blank frame of negative film to cancel orange mask?

[imaginator]

Has anyone tried shooting a blank frame of color negative film to use

for correcting the orange mask? How can I use this scan in photoshop

to "reverse" the orange mask? Am I missing something, or would this be

the best way to deal with variations in the mask with different films,

even one's not listed in the scanner software?

[john_corb]

if you want to try doing in ps then a direct route is... put the mask on one layer, the

image on another, set layer blend to difference mode, merge layers, then invert (i'm

just thinking through these steps, haven't tried it but it should work)

 

unless you scan at a reasonable bit depth, you will lose dynamic range doing

things this way

 

this process may not be that useful, the scanners i've used seem to handle variations

in mask ok, you will still need to correct the images for variations due to the colour

temperature of the illumination

[alan_schietzsch]

This works, assuming your scanner has sufficient dynamic range. One trick is

to scan only the centre part of a frame and then median/blur it to a consistent

frame where every pixel is the same colour. This eliminates any grain

contribution from the mask frame.

[leonard_evens]

What scanning software are you using. All the scanning software I'm familiar with will remove the orange mask automatically. Some even allow you to specify the kind of film so they can do a better job of it.

 

Many of the people who ask this question are trying to scan negative film with a flatbed reflective scanner, which is going to produce disappointing results no matter how you go about it.

[imaginator]

I'm using an inexpensive 35mm film scanner... relatively low dynamic range. I didn't think about the "grain" issue, thanks for pointing that out. Actually, I'm using the scanner for slides right now, but want to try some negs soon. I might take a different approach to this, and just use the blank frame scans as a reference to compare different print films, instead of using them to directly alter the color of the image. I'm going to shoot a blank frame of each different film I use, and if nothing else, it will give me a good idea of the variations.

[emre]

<a href="http://www.hamrick.com/vuescan/html/vuesc5.htm#topic4">Vuescan can do this for you</a>.

[franciszek_czekala]

It would be better to photograph a special color pattern and then use it as a source for proper color correction. Picture Window Pro has a transformation that does exactly that and it uses a standard industrial color card for this purpose (I do not remember its name though). All necessary brightness/contrast/color corrections can then be saved to disk and applied in one fell swoop to other frames. It seems to me that a blank frame will be too thin to be used with good results. Moreover different corrections may be needed to get different colors right - it is because each film has its own color characteristic, which means that different hues have different color shifts. I dare say that scanning just a blank frame will not be much useful if your goal is to improve the color rendition in comparison with standard scanner software. You must have some well defined and varied information present in the frame to get things right. Since a standard color card is such a well defined source of color/brightness information it can be used for this purpose. Picture Window Pro has an option that enables you to manually define where in the frame are the appropriate color squares that make up the card and it even can take care of geometrical distortions if the card was not exactly parallel to the film surface when it was photographed. To be quite truthful my experience with Picture Window Pro was that enables you get things right with your photographs even without this kind of calibration and it works with 16-bit color files. Forget Photoshop and get software that does real useful job. And it costs only 90$.

[rainer_viertlb_ck]

you have to correct one grey tone at the highest, one grey at the lowest and one in the middle of the tonal range. you correct the low end and the high end with the range parameters of the three colors, and finally the midtones with the gradation curves of the three colors. if your scanning software allows this you will reach very good scanning results for your negs. you can do this also in photoshop. but the result will be more bad than if you do it in the scanning software.

for correcting in photoshop shoot three grey pictures. one with a exposure 4 or 5 app. ( should be nearly white )above your exposure, one correct exposed ( grey )and on 2 or 3 app. underexposed ( nearly black). correct this three grey zones in the gradation page in photoshop and you will get it.....( with much patience and thinking about what you are doing...)

[sk_arts]

I have a book that goes over something similar, I will have it returned to me soon and will email you with an adaptation.