The Difference Between Black & White vs. Monochrome
Just what makes a digital photo black and white?
Technically, all digital photography starts out as black and white. There’s no such thing as a color sensor. Color photography happens by capturing monochrome image information after it passes through red, green and blue colored filters. These filters are part of the CFA (Color Filter Array) that’s printed on top of the monochrome sensor. The standard type of CFA used in most digital cameras is called the Bayer Filter Mosaic, and is basely closely on human vision. On top of this array are tiny lenses which focus the light through these filters and onto the photo receptors on the chip.
The term “monochrome” literally means, “one color”. All black and white images are monochrome images, but not all monochrome images are black and white. Other types of monochrome images include sepia, or other “toned” images, and cyanotypes. They all have one hue of color rendered in different values, or luminosity levels. But a black and white image is a monochrome image using only neutral shades of gray, also known as “luminosity, lightness or value”. “Grayscale” is actually a more accurate term for black and white photography.
But, unless you’re shooting with the $6,200.00 Leica Q2 Monochrom camera, to make a black and white image you have to remove the color information that your camera captures. So, a digital black and white image starts out as black and white, is converted to color, and is then converted back to black and white. There’s no such thing as a monochrome Raw file. All Raw files contain color information. But, when you have your camera set to monochrome, it flags the Raw image using metadata to tell Raw processing applications to assign the appropriate monochrome camera profile which translates all the color information to luminosity information. This can easily be undone, so that you can restore to the color to these monochrome-like Raw files.
This may seem silly, but there’s both an upside, and a downside to all this. The downside is that this process (called demosaicing) yields a black and white that’s not as sharp as if we captured only the luminosity information. The upside is that since 3 images have been captured through red, green and blue filters, we have a lot of options to control contrast.
That’s right, each color image consists of three black and white images, each shot through a red filter, green filter and blue filter. If you took three identical shots on black and white film through red, green and blue filters and pasted them into their respective channels in an RGB image, you’d have a color image. Perhaps not perfectly accurate color, but pretty close.
So if your intention was to shoot a black and white landscape through a red filter, using just the red channel is a good starting point. And if you’re shooting a black and white portrait, the green channel works well because green filters are used to enhance skintones. For orange and yellow filters, you use a combination of the red and green channels, which can be accomplished using the Channel Mixer adjustment layer in Photoshop.
A more intuitive way is to use Photoshop’s Black & White adjustment layer, which uses the combined RGB information to break the image into six individual channels based on color. Similarly, Camera Raw and Lightroom give you eight channels to work with in the B&W Mixer panel. You can also use the Hue/Saturation adjustment layer in Photoshop, which gives you an infinite number of channels because it allows you to select any hue.
So the black and white digital photography we all know is somewhat of a compromise. While the red, green and blue filters are handy, they don’t have the accuracy of optical filters, and they reduce the sharpness of the image. So it’s always important to use the sharpest lenses you can, which is why prime lenses are a good choice. And knowing how to best sharpen your black and white images is also important.
But to shoot the cleanest and sharpest digital black and white, you need a dedicated black and white digital camera, and there are only a few very expensive options, one of which is the Leica mentioned above. The Leicia M10 and Q2 Monochrom cameras do not have Bayer CFA’s on their sensors, and so they only capture luminosity values and save them as .DNG files, not Raw files. Although they’re very similar, there’s no color information to recover from these .DNG files, so they are true monochrome images. And since they have not gone through the demosaicing process, they are considerably sharper than Raw files that have. To get extremely sharp black and white images on a budget, shooting black and white film and having it scanned to a digital file is the most economical way to go. But there is another solution.
You can have your camera (or a used model) converted to monochrome through “Debayering”, the process of scraping the CFA and micro lenses off the sensor so that it only captures luminosity information and turns it into a true black and white digital camera. The twist here is that the demosaicing algorithm is still at work, so the images have to be processed to “undemosaic” them using specialized software. This would create an image on a par with the Leica Monochrome and traditional black and white film. Incidently, if you’ve recently had a camera converted to IR or Full Spectrum, try using that, as the removal of the Hot Mirror/Low-Pass filter will also improve sharpness to some degree.
All that being said, how can we get the best quality black and white images from the Raw images we have? Is there a way to produce a Raw black and white file without using a monochrome camera?
The practical answer is, “Yes!” the color information that is captured in a Raw file is easily translated back to luminosity-only information. You simply set your camera’s “Picture Style” or “Picture Control” to monochrome, and the Raw image is flagged as such so it appears as a monochrome (black and white) image when you open it Camera Raw, Lightroom or another Raw processing application that recognizes the monochrome flag.
With up to 14 bits of tonal information, a Raw file can contain 16,384 shades of gray and 4,398,046,511,104 (over 4 trillion) colors. So with all that information to work with, Raw is the best place to do the conversion. By default, CR/LR will use a Camera Monochrome profile for your camera model if one is available. If not, or if you wish to use the powerful B&W Mixer panel in CR/LR, use the Adobe Monochrome profile. This splits the RGB-filtered information into eight color channels that you can use to control local contrast.
The next best approach would be to open the images as 16-bit ProPhoto RGB or LAB Color images, which would retain all the color and luminosity information present in the Raw capture for you to use with Photoshop’s B&W tools (Channel Mixer, Hue/Saturation or Black & White) or third-party plugins (such as NIK Silver Efex Pro). Keep in mind though that unless you open the Raw image as a Smart Object layer, there are no longer any white balance tools or camera profiles in this working space.
Another option is to use other Raw processing apps such as DxO OpticsPro 10. This tool does what Camera Raw and Lightroom do, with dedicated features for black and white. Unlike CR/LR, it offers an option to simulate black and white film grain through the DxO FilmPack extension. Learn more.
Whichever tool or method you use, monochrome and black and white photography has become easier and more fun to work with than ever, and yet we can still approach it using more traditional methods if we choose to.
