PSD: Duotones

01. What is Duotone?
02. What a Duotone can do?
03. What ink Duotone is used for?
04. Is Duotone is in RGB or CMYK mode?
05. How do i change my image to duotone? the Duotone is grayed out.
06. What are the boxes in the Duotone dialogue box?
07. What is duotone curves?
08. How do i preserve the setting on the curve?
09. How do i see the ink percentage of the final output?
10. What is Overprint?
11. What are the numbers in the overprint dialogue box?
12. How do i see individual channels of duotone, once iam done.
13. How to Print duotone?
14. How to export duotone to other applications.
 
01. What is Duotone?
Duotone refers as two ink, Grayscale images like monotone are printed with single non-black ink and to duotone, tritone and quadtones are grayscale image with more than one ink. Colored inks rather than different shades of gray are used to reproduce tinted ink.

Duotone option box has four ink options to select, based on the type you select (monotone, duotone, tritone and quodtones) you can specify the ink color on the color box.

02. What a Duotone can do?
Grayscale reproduction can display 256 levels of gray in your monitor, but on a printing press reproduce only 50 levels of gray per ink. By adding duotone or tritone or quadtone you can have more shades of gray, each individual ink can produce upto 50 level of gray.
 
03. What ink Duotone is used for?
Sometimes duotones are printed with black and gray ink. Black for shadow and gray for highlight and midtones. To increase dynamic range of the images, duotones are printed with color inks.

04. Is Duotone is in RGB or CMYK mode?
Duotones are 8 bit grayscale image and you do not have individual channel in the channel panel, like you have on RGB and CMYK and Lab. You have only one channel.

05. How do i change my image to Duotone? the Duotone is grayed out.
Before you choose the mode to duotone you must convert it to grayscale, this will flatten all the channels into one gray channel. After converting to gray scale,  you can able to select the duotone mode. By going to Image > Mode > Duotone.

06. What are the boxes in the Duotone dialogue box?
Based on the type you select, the ink option box will activate. Montone with one ink, duotone with two ink, tritone with three ink and quadtone with four ink. To control the ink percentage you can use the curve option box before each and every color box.

07. What is Duotone curves?
Duotone curve will give you full control over a shadow and highlight on a image. The curve maps each grayscale value in a orginal image to a specific ink percentage.

Default straight line on the curve indicates the equal ink percentage. Shadow is on the right with 100% and highlight is on the left which is 0 value. The grids are defined as ink percentage, which you can able to add the value on the relevant box towards right or you can move the curve to automatically add the value in the box.

You can add upto 13 points on the curve, 13 boxes on the right. Moving the curve up will increase the percentage and moving it down will decrease the percentage.

08. How do i preserve the Settings on the curve?
You can save your curve values by clicking the ‘Save’ button on the right and you can even load the curve to apply the previously saved settings.

09. How do i see the ink percentage of the final output?
You can use the info panel to see the actual print output color by changing mode to ‘Actual Color’ in the info panel menu. The values will reflect any changes you made inside the duotone curve dialogue box.

10. What is Overprint?
Overprint are two unscreened ink printed on top of each other. Overprint will be based on the ink you specify on the ink color box

11. What are the numbers on the Overprint dialogue box?
Its the combination of ink mixture from Ink color you specify on the duotone dialogue box. By clicking on the color box in the overprint dialogue box you can able to adjust the color combination.

12. How do i see individual channels of Duotone? 
Before you bring up the duotone dialogue box, we have discarded all the color information of the image and flatten the layers to single grayscale channel. The duotone colors are applied directly on the original image as a final result. But in some cases if you want to see the colors in different channel then you have to convert to Multichannel mode to separate the colors.

Image > Mode > Multichannel, the image is converted to multichannel mode and all the color are separated and represented as a spot color channel. The channel color information are based on the duotone color settings, but sometime these color information on channel might not be exactly as the duotone settings.

13. How to Print Duotone?
In duotone the order in which the inks are layed out and the screen angle of the printed plate have a significant effects on the final result. To produce a fully saturated color, keep the darkest ink on top and lightest ink at the bottom.

You do not need to convert the duotone to CMYK for separations. Before you print the image go to ‘Print dialogue box’ and on the Color Handling pop up select Separations.

14. How to export Duotone to other applications.
Before exporting your Duotone image to other page layout applications you need to save as EPS or PDF format, if your image contain spot channel then convert it to multichannel mode and save it as DCS (Desktop Color Separation) 2.0 format. Naming your channel with appropriate suffix is very important or else other application won’t print the color correctly.