Beginner When is Black & White ACTUALLY Black & White?

Forkbeard

Forkbeard

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Jim
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I've been playing around with some black and white portrait shots and noticed that by turning the saturation right down or greyscaling the image, it doesn't actually look black and white, it looks more a blueish tinged b&w. With the blue channel turned down a bit it looks more of a 'classic' black and white, at least to my eyes. Is this maybe down to my screen? Or am I just imagining black and white a certain way, maybe associating it with 'old' and expecting a certain colour cast due to ageing?
Is converting an image to black and white as simple as desaturating it (colourwise I mean)?
 
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Forkbeard said:
Is converting an image to black and white as simple as desaturating it (colourwise I mean)?
Click to expand...

Yes it is… No it is not… :confused:

Luminance and chrominance have each their res-
pective way to impress a given capture.

For example, in a scene with very deep colours of
greens, browns, reds, blues etc, all will be distin-
guishable as long as the colours are maintained.
Desaturating the picture removes the chrominance
values AND the included luminance as well. This
will result in a darker image where the only remedy
is the shadow recovery slider and its consequences
— having lost the individual colour channels.

Converting to B&W will preserve the said luminan-
ce values and ADDs the corresponding luminance of
the concerned chrominance. This conversion of the
colour values, in terms of luminance, will keep track
of the original chrominance values converted in added
luminance and offer the precious ability to balance the
different chrominance channels (6 in all!) of an image
as easily as using an audio equalizer!
 
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Phil V said:
Is your monitor calibrated regularly?
Click to expand...


No, I did it a while ago, but to be honest probably didn't have colour cast in mind - more contrast,sharpness etc. Anyway, I just did it and dialled back the blue channel a bit and it looks OK. Everything looks 'normal' but the weird smoke blue tinge has gone from the b&w images.

It's ironic that it takes a black and white picture for me to notice my colour is off :)
 
By the way, can someone tell me what is actually happening when I choose grayscale? I still have some control over colour with grayscale but not with desaturate.
 
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Kodiak Qc said:
Yes it is… No it is not… :confused:

Luminance and chrominance have each their res-
pective way to impress a given capture.

For example, in a scene with very deep colours of
greens, browns, reds, blues etc, all will be distin-
guishable as long as the colours are maintained.
Desaturating the picture removes the chrominance
values AND the included luminance as well. This
will result in a darker image where the only remedy
is the shadow recovery slider and its consequences
— having lost the individual colour channels.

Converting to B&W will preserve the said luminan-
ce values and ADDs the corresponding luminance of
the concerned chrominance. This conversion of the
colour values, in terms of luminance, will keep track
of the original chrominance values converted in added
luminance and offer the precious ability to balance the
different chrominance channels (6 in all!) of an image
as easily as using an audio equalizer!
Click to expand...

Hi Kodiak. By 'converting to black & white' do you mean using grayscale rather than desaturate?
 
Forkbeard said:
Hi Kodiak. By 'converting to black & white' do you mean using grayscale rather than desaturate?
Click to expand...


No, converting to B&W means creating 6 colour channels
so to add their respective luminance to each channel and
so retaining all the flexibility.
Forkbeard said:
can someone tell me what is actually happening when I choose grayscale?
Click to expand...
Converting to grey scale means you reduce the file size by
throwing away the chrominance —keeping the luminance—
losing the channels after the conversation.

I would never recommend to simply desaturate any image!
 
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Phil V said:
Is your monitor calibrated regularly?
Click to expand...

My first thought too. If an image is desaturated then any colour you perceive is being added by the viewing equipment, though you should bear in mind it can take a little time for the eyes to settle down if they have just viewed a brightly coloured image.
 
Forkbeard said:
No, I did it a while ago, but to be honest probably didn't have colour cast in mind - more contrast,sharpness etc. Anyway, I just did it and dialled back the blue channel a bit and it looks OK. Everything looks 'normal' but the weird smoke blue tinge has gone from the b&w images.

It's ironic that it takes a black and white picture for me to notice my colour is off :)
Click to expand...
Are you using a hardware calibration tool, a software tool or just 'doing it by eye?

And as above, a good B&W conversion gives control over the look of your image by choosing the different channels.

Never simply desaturate, it gives a very muddy grey mush where there should be crisp separation of tones.
 
Phil V said:
Are you using a hardware calibration tool, a software tool or just 'doing it by eye?

And as above, a good B&W conversion gives control over the look of your image by choosing the different channels.

Never simply desaturate, it gives a very muddy grey mush where there should be crisp separation of tones.
Click to expand...


I did it by eye in Windows 10, which I realise is not the way to go. I've now undone it and put it back to how it was. As Ancient Marnier said above, it could just be my eyes anyway, I also have no real idea what I'm doing so...I reset it.
 
Forkbeard said:
I did it by eye in Windows 10, which I realise is not the way to go. I've now undone it and put it back to how it was. As Ancient Marnier said above, it could just be my eyes anyway, I also have no real idea what I'm doing so...I reset it.
Click to expand...
Re-setting it doesn't make it 'right' ....
 
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