Was bored, so made this...

[Bozothenutter]

To illustrate the caveats of B&W picture colour guesstimation, I made this:

Though it is far from scientific ( I have no access to actual film properties data), I think it shows nicely what I mean.

Image was taken from Armorama, model is by 'Carius Modeller'

 

The premise is that in B&W photography (with film) it was almost standard to have a yellow/orange/red attached to the front of the lens to increase contrast.

This will skew colour representation in B&W pictures to quite some extent.

As older films were quite low contrast (google orthochromatic/panchromatic) the filters were used to make the image 'pop'.

Since I have no histograms of older films and don't really have the knowledge to translate these into usable data, the film specific properties have been left out of the equation.

 

Original image:

downloaded and converted to grayscale

Grayscale:

Well, its grayscale....

Red:

original image with only RED 'colour balance' slider in GIMP set to +50, then converted to grayscale.

Magenta:

original image with only MAGENTA 'colour balance' slider in GIMP set to +50, then converted to grayscale.

Green:

original image with only Yellow 'colour balance' slider in GIMP set to +50, then converted to grayscale. (apologies for the confusing name, but the image turned green....)

I have a larger version of this image, but cannot upload it to postimage

 

some good info here:

https://www.ilfordphoto.com/colour-filters/?___store=ilford_brochure&___from_store=ilford_uk#:~:text=Normal black %26 white films are,respond to the different colours.

https://hoyafilterusa.com/pages/how-black-white-filters-work

 

 

[JackG]

There is a free demo software available that emulates both ortho and panchromatic film, as well as coloured filter options:

 

http://powerretouche.com/downloads.htm

 

 

regards,

Jack