Color to Grayscale

[Deleted member 82967]

Comparing Color to Grayscale Methods

There are several methods of converting from color to so-called black and white. An application can offer an RGB channels mixer; or no choice but what the app does; or a drop-down list or buttons for various methods such as 'Luminance'. The GIMP offers a good few:

8.31. Desaturate

Here's how they look when applied to a good old Macbeth card color image:

At first glance, they look the same but have a close look at each card's third row of primary and secondary colors (blue, green, red, yellow, magenta, cyan):

In the upper images, there is little tonal difference between the patches. Which implies that mere color differences in an actual scene would show little contrast after conversion ... think pool balls ... a slightly brighter yellow patch at left, I reckon. Much more contrast in the lower images' third row - with the yellow sticking out like a sore thumb! The image at left showing noticeably more contrast than that at right, even in the light brown wall paneling. Of the four methods used, the lower left (luminance) looks best to me. Some might prefer the lighter rendering of the first two rows offered by the lower right (Value).

So now I know why the most commonly recommended method is 'Luminance'

Comments welcome!

 

[Chriscrawfordphoto]

None of those methods really work well. The problem with converting a color digital image to B&W is that the midtones are always very flat and lifeless. Increasing overall contrast doesn't help because it blows out the light tones and pushes the dark tones down too far. This is why B&W conversion plugins like Nik Silver Efex Pro and Topax Black and White are so popular; they take care of that for you.

You can get good results just using Lightroom or Photoshop, but it takes more than just converting to grayscale to get good tonality. Here are videos I made showing how:

Lightroom

Photoshop

 

[Godfrey]

Agreed, Chris ... although I have my own methodology for doing B&W rendering from RGB raw files in Lightroom.

I use mostly the HSL control panel (saturation on all channels set to 0, luminance shaped to suit two different filter notions—essentially orange and green B&W filters) to achieve a first cut, then manipulate the rendering through the Tone Curve rather than using all the other controls.

I should write this up more formally, but no time right now.

G

 

[Deleted member 82967]

None of those methods really work well. The problem with converting a color digital image to B&W is that the midtones are always very flat and lifeless. Increasing overall contrast doesn't help because it blows out the light tones and pushes the dark tones down too far. This is why B&W conversion plugins like Nik Silver Efex Pro and Topax Black and White are so popular; they take care of that for you.

You can get good results just using Lightroom or Photoshop, but it takes more than just converting to grayscale to get good tonality.

Quite so. Fortunately, I was just comparing four methods rather than striving for the ultimate in tonality. Thanks for the advice but I neither own nor use Adobe products.

The GIMP's 'C2G' was quite fun ... Ansel would have loved it ...