The Color Modes: Grayscale

This is the second in a series of posts discussing the color modes in Adobe Photoshop. One of my previous posts, ‘256 Shades of Gray: A Ribald Tale of Bit Depth’ covered the color modes available in Photoshop when starting a new document. This series of postings will go into each one of those modes in a little more depth plus cover the other secondary color modes. My goal is to keep things simple in this blog. So I won’t be going into much depth with bit-depth. I’l just go a little bit…in depth.

The Grayscale Color Mode in Adobe Photoshop

When you are only printing one solid color, but want tints or screens of that color. The color can be black, white or any single ink or spot color. But check with your print vendor to see how they handle whites. Not all printers are equal when it comes to printing white.

The Grayscale color mode in Photoshop is pretty much the same as the Bitmap mode, but with the ability to tint your single color with varying percentages or levels.

When starting a Grayscale file you have the option to choose 8-bit, 16-bit or 32-bit.
Which ‘bit’ option should you choose? Well the standard is 8-bit. 8-bit is universal when it comes to which print vendors and which equipment can handle that level of print quality.

8-bit will give you 256 shades of gray…if you count black and white in with that 256. 16-bit will give you 65,536 shades of gray and 32-bit…will give you a whole bunch more. When it really comes down to it, who needs to know a number? Essentially, the higher the bit depth - the more colors you have, meaning gradations looks better and colors have the potential of being more varied and vibrant.

32-bit and higher should only be consider for HDR or High Dynamic Range images. This is most thought of for use in color images but can benefit grayscale as well by offering more steps between you typical darks, mediums and brights.

Consider using 32-bit Grayscale if you are planning on printing an image with a single spot color. You could create or retouch an image in 32-bit, then assign a single spot color ink instead of black ink to see if the image pops more. You could also create or retouch the 32-bit Grayscale image to your liking, then duplicate the one grayscale channel to four separate channels or plates printing in CMYK to create a dynamic effect.

Grayscale comes in handy when you are creating a line of packaging that may have a number of variants with a common image, but with a different variant spot color on each package, label or wrap. Use the same grayscale image for each, but assign the different spot color for each package when sending out the final art.

It comes down to knowing who is printing your job and what their capabilities are. If we are strictly talking about ‘on-screen’ viewing - all bets are off and you can do whatever the quality of the viewers monitor can handle.

For the most part, you should stick to 8-bit for your Grayscale, but experiment with higher bit depths and research HDR for higher end photography and retouching.

Black Isn't Always Black

When working with blacks we frequently take it for granted that black will print a nice rich deep darkness as is the default on-screen appearance in Adobe Illustrator. That’s not the case if you consider 100% printed Process Black ink. In reality 100% black ink prints as a dark gray. This is most apparent if the print is uncoated. A varnish printed over 100% black ink will help to deepen the black.

This why it is important to check your black color mix in your Color palette in Illustrator and to set your ‘Appearance of Black’ in Preferences as ‘Display All Blacks Accurately’.

With the blacks displaying accurately you will get a better idea of how your print may look. It will also give you a clue about whether or not you should use a Rich Black mix.

Rick Black (frequently referred to as CMYK Black) is essentially 100% Black ink with an even mix of Cyan, Magenta and Yellow inks. Each printer has their tried-and-true method of printing Rick Blacks. You should check with your printer what that mix is. It’s usually 100% K and 60%-70% of CMY. Also, clearly define in your color break, on your final release file, what needs to print 100% Process Back and what needs to print Rich Black.

You’ll always want to print your black type as 100% Black, otherwise the the type will print fuzzy. But if you have large areas of black in photographic or illustrative images which employ strong areas of black, you’ll want to ensure that those areas print a CMYK Black.

If you are limited to the amount of color stations you can print and you must include some spot colors in your job...requiring you to eliminate all or some of your CMY, you may be able to use some of those spot colors mixed with Black to simulate a Rich Black. Work with your printer on what that mix should be.

You should also pay attention to your Black mix in any Photoshop files placed within your Illustrator file. You’ll want a mix of colors (whether CMY or Spot) with your Black to give your images a richer look. But if you have fine lines or type in your Photoshop file that are printing Black, you’ll want to make sure it is printing only Black. But, on the other hand, any fine line work or type should be created directly in Illustrator.