Adjust resolution to enlarge image.
Don't increase above 300 dpi for print.
CMYK colour mode for print.
HOWEVER.....
Photoshop prefers to work n RGB.
Some applications don't apply to CMYK so will not work.
SO WORK IN RGB IN PHOTOSHOP.
Applying Colour
Hue
Saturation
Brightness
G:255% =100% green
Convert from RGB to CMYK
Changes due to it being out of the CMYK gamut, uses the nearest colour available.
Need to avoid an unexpected colour shoots.
Typical digital RGB image
'View gamut warning'
Grey area indicates a warning to the colours which are not printable, they will be shifted into the nearest printable colour when converted into CMYK.
Use 'Image' //'Adjustments' to rectify these out of gamut colours.
Decrease saturation.
Brightness/contrast levels.
'Replace colour'
Use eye dropper over the image.
Samples colour.
White area is the area selected.
Increase fuzziness = increased area selected.
Then adjust saturation and only selected area is affected.
Proof colours.
How it will look when it's converted to cmyk.
Hover over swatch with colour picker. Hold 'alt' and delete.
! Shows colour is out of gamut range.
Click on icon to pull colour into gamut range.
Add to swatches.
OR click on empty area in swatch palette to add colour.
Sample colour from image and create swatch from that colour.
For spot colour can use colour libraries.
Can type a reference to find swatch.
Hold atl +delete will fill selection with foreground colour.
shift + delete will fill with background colour.
Now needs 4 printing plates to print.
To work with spot colours in CMYK
Using Spot Colour
Open greyscale image.
Click on black colour box to select colour.
Open swatch library.
View colour reference.
Now monotone file.
Colour can be easily changed by opening up menu again.
If image added to inDesign, the pantone reference will be transferred.
Change how that colour is mapped to colour scale.
Greyscale bar along bottom is the shades of grey in image.
New colour values along other axis.
Like for like replacement of ink if straight diagonal line.
2 Spot colour
Pick second colour.
Apply ink to different parts of original image using curve.
...new inks are mapped to different parts of original greyscale.
Approximation shown in bar.
When this image is added to inDesign both pantone values are imported with the image, you can easily use the same 2 spot colours within your design.
Second Technique
Use channels palette
For greyscale image
CMYK image
Channels can store information about an image.
When selecting, can save a selection to go back to later.
Alpha channel contains information about selection.
Colour is transparent. The blue ink will overprint the black ink.
Now have 2 colour channels
Specifies where spot colour will be applied.
Can use photoshop tools to edit spot colour.
New spot colour made with nothing selected. Then apply gradient tool.
For a varnish you would use a spot colour that you weren't using in publication, then ask at printer to not print colour but varnish instead.
No comments:
Post a Comment