- Colour modes available to use
- RGB - additive process
- All image files are always in RGB colour mode, but we need CMYK for print.
- RGB has a broader colour spectrum available than CMYK, hence the difference between the two colour modes.
- RGB has a greater range of colours than CMYK - also known as GAMUT.
TO CHANGE COLOUR MODE:
- Use the 'image' menu and choose 'mode' then select the chosen mode.
WHY WORK IN RGB?
- When changing a image that is set in RGB to CMYK you will see that the colours will change within the artwork as the RGB colour range wont be available in the CMYK range.
- More options are available to use when working in RGB
- Photoshop is designed to work in RGB, so all options etc are only available in RGB mode as it is the default mode, meaning it is advisable to work in RGB to get the best from photoshop.
- RGB are smaller files.
WHEN WORKING IN RGB:
- use gamut warning to display the colours which won't be printable - this will be shown by grey areas.
These colours are not predictable to know what they will print like and could ruin the artwork.
To bring these colours into the CMYK range to be able to print you can do it in the following ways:
- use the HUE/SATURATION
- use the LEVELS
These options are a good way of editing the image, but it does change the whole image, whereas you could use the ADJUSTMENT LAYERS just to edit the selected areas which are out of the CMYK range to make it printable.
USING PROOF COLOUR:
- the image turns to RGB & CMYK - this turns on the CMYK preview, so you will see how it looks when will be printed, but the image is still RGB, so you can use all the tools within photoshop.
Images for print from photoshop should be converted to CMYK before you save and to use to print or within another software.
SWATCHES WITHIN PHOTOSHOP
- To delete a swatch colour from the swatch palette, hold down 'ALT' and then click on each colour.
- Use 'D' to reset foreground and background to black and white.
- To add a swatch to the swatch palette, click in the swatch palette when the foreground colour is selected.
- To open a swatch palette use the palette menu and choose 'replace swatch'
- Use 'save swatches for exchange' to use within another adobe software
CREATE OWN SWATCH LIBRARY
- use the colour picker
- use the colour area to choose colour, but remember to choose a colour which is within the CMYK range
The exclamation mark comes up when out of CMYK range - move colour picker so it disappears or click on the box and it move to nearest available CMYK colour.
- once you have chosen the colour you want, click 'add to swatches'
- You an also choose the colours by using the colour palette and then click into the swatch palette to add it to the palette. But remember to change to CMYK colour mode within the colour palette.
LAB COLOUR:
A Lab color space is a color-opponent space with dimension L for lightness and a and b for the color-opponent dimensions, based on nonlinearly compressed CIE XYZ color space coordinates.
HOW TO WORK WITH SPOT COLOURS
Opening spot colour libraries:
Open the colour picker and select 'colour library'
This will open the colour library
which you can select the pantone library you want to use, you can also type the reference number to find the pantone colour you want.
- When using a spot colour straight from the library it will mix the colour from CMYK, so it is not an actual Spot Colour with the same reference number.
TO GET AROUND THIS:
- use a black and white image to create a duotone image
- This works by the spot colour overprinting the black and white image to use the grayscale to accent the spot colour.
METHOD 1:
- First convert the image to GRAYSCALE
- Then choose DUOTONE from the mode menu.
- Working within the monotone type:
- Change the ink 1 to the colour you want to use - spot colour
Choosing the spot colour and identifying this by the spot colour reference number being used.
- Once you have chosen the colour you want, if you want to change this you can go back into the duotone options and change this colour.
- To edit the duotone you can use the curve next to the colour you picked in the duotone options to change the effect of the duotone on the image
USING MORE THAN ONE COLOUR ( DUOTONE ):
- work in the same way as above except choose a second spot colour
- To apply the DUOTONE work in exactly the same way as before, to choose and edit colours.
- This works black and one more colour.
Useful if you are wanted to produce artwork/layout with one or two spot colour and everything to be the same spot colour or tints of.
METHOD2:
- Doesn't need the image to be grayscale can be in ANY colour mode
- Understanding of CHANNEL PALETTE - splitting the image into the different colour components.
RGB - Red // Green // Blue
CMYK - Cyan // Magenta // Yellow // Key
- When you click on an individual channel, it will display in grayscale, each colour is more present in the darker areas.
You can use the selection tools to select a certain area of an image and make this selection into channel by using the 2nd icon from the left at the bottom of the channel palette.
once this selection has been made you can edit it by using the paint tool on black to add to the selection or white to subtract from the selection.
USING SPOT COLOUR:
using the channel menu option - select 'new spot channel'
once chosen the colour you want to use, make sure the reference number is shown then click OK. The spot colour is then added to the channel palette.
Using the paint tool on black you can start to apply the colour to the image. As you can see adding the colour doesn't get rid of the initial image below, it is an overprint on the original colour and just adds colour to it. (Like overlay blending option)
- changing the solidity of the spot colour is like changing the transparency of the colour, the closer to 100% the more solid and flat the colour becomes.
- When saving the file, save as photoshop or tif file and make sure 'spot colours' is checked.
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