When scanning color negative film you face the task of removing the orange mask in the negative to restore the colors for the digital image. I have tried several scanning software and other free and commercial methods but never have really been satisfied.
While tweaking a scan in Photoshop I discovered a method that seems to produce consistant and good results: divide the raw negative scan with the orange mask color.
You will need:
- a scan of the orange mask (one per roll of film)
- raw scans of your image frames, all scanned with the same exposure settings as the mask scan
Step 1: Scanning
I use VueScan Professional for scanning so the scanning instructions are for that software. I’m sure it is possible to get the same results from other scanning software.
Load your film strip into the film holder and do a preview. Make sure that “Lock Exposure” is unchecked. Set all cropping options to manual. Then select a part of the film strip where only the orange mask is visible.
Do another preview. After it is done, check “Lock exposure”.
Make sure that you are saving the raw scan and set the file name. Scan the image.
After this, scan all your frames keeping the exposure locked. Step 1 is now done.
Step 2: Remove the orange mask in Photoshop
Firstly, open your mask file in Photoshop. Use the color picker tool to set your foreground color to the mask color. Use a larger sample size to get a nice average color of the mask. For the next steps, it is important that the mask color is selected as the foreground color.
Now open a raw scan of a frame from your film strip.
You can create an action of the following steps.
From the Photoshop menu, select Layer / New Fill Layer / Solid Color. In the dialog, change blend mode to Divide.
Click OK and accept the current color in the color picker. Your layer palette should now look like this:
From the menu, select “Layer / Flatten Image” and then “Image / Adjustments / Invert”. The orange mask is now removed and the image is positive.
Tweak the white balance and brightness settings either manually or automatically. Image / Auto Tone usually does a decent job:
Alternate step 2: Remove the orange mask without Photoshop
Most likely, several image processing software can be used to perform step 2 (please leave a comment how to do it in your favourite software).
I have written a script called negdiv.sh to remove the orange mask. It also has an option (-a) to execute Fred’s autotone.
(Sorry, the script is for Mac/Linux users only. I know it can be converted to Windows but I don’t have the resources to do that. If you want to, please go ahead. The script is GPL licensed.)
This is the same image processed with negdiv and autotone: