is Index Color Separation?
Why use Index Color separation?
Halftone dots form an image by varying the size of the dots. Different sizes produce different shading, many different shadings form an image/design.
Diffusion dither random dots are all same size, it form an image by varying the distance between the dots. Different distance produce different shading, many different shadings form an image/design.
Below are the comparison between Index Color and traditional CMYK halftone to see why Index Color stands out as a better solution for t-shirt printers.
2. color shift
3. over saturate
4. color fade
of Index Color
use Index Color?
What happen if you're
going to index a detail illustrated smoking gorilla with small but clear
wording attach on the cigar and an obvious shadow fade out behind?
NO PROBLEM! You can make both the index color Diffusion Dither dot pattern and the halftone dot pattern exist simultaneously in one color/film. How? Please click here to find out.
Separation step by step guidance :
Step 1 :
Make sure the
design is in RGB mode.
Set the image
(pixel/inch) depends on how you want the result on t-shirt looks after
Step 2 :
Analyze the design, look for primary colors in the designs (Red, Yellow, Blue are good example). These are colors that CANNOT be reproduces by mixing any other colors together. Leave secondary colors behind, these are colors that can be reproduced by mixture of primary colors.
motorcycle image :
Pick the secondary colors only if you still have extra places after choosing all the primary colors.
Now you have the primary color concept clear. Okay, here is a more precise one : "Always pick the MIDTONE primary colors". Never pick dark primary colors. Dark primary colors are consider secondary colors because they can be reproduced by mixing themselves with black or darker primary colors.
Keep in mind that any color which can be reproduced by mixture of any 2 other colors is NOT a REAL primary color.
You are now well equip to pick the best set of color for any design. Of course with a few trial and true instead of error.
5.0)Action : image > mode > Indexed Color...
mode > Indexed Color...
Step 3 :
Color Table pop-up, make sure all the small color boxes are in complete white. If not, select all the boxes (click the most upper left box & drag to the most lower right box), Color Picker pop-up, pick the complete white color (R=255, G=255, B=255), click OK, click OK again.
Click the first box, base on what you have learn, pick your first index color from the design with the Eye Dropper tool, you can move around searching for the best choice, after confirm, click on the spot, click OK.
the color palette until the last color which is usually the black.
Click OK at the Color Table, click OK again at the Indexed Color pop-up to see the result. (You only click OK once at the Color Table for Photoshop 3.0)
Zoom to 100%(Photoshop 5.0) or 1:1 (Photoshop 3.0) or bigger to study the color picked. The image/design looks cracked below this size.
Move around, analyze the image part by part, keep UNDO (command-Z/Ctrl-Z for PC) and REDO (command-Z/Ctrl-Z for PC) between RGB and Indexed Color mode to study the changes and you will see whether you chose the correct colors and which color you should rechoose or which color you should drop (if you chosen the wrong one). This is the most direct and effective way to improve your separation.
Nobody will satisfy with the first try.
Tips : Don't ever think that the Index Color separation process looks too complicated and making decision to purchase a color separation software to solve this. This is a wrong perception. Separation software is a system. You need a good color concept to backup a system. You still have to decide which color to pick in the end, automated color picking still not that intelligent... yet, to pick the correct set of color.
Once you are satisfied with your final set of colors, save the color palette (CLUT-Color Look Up Table). Image > Mode > Color Table..., click "Save" at the Color Table, enter a name for the palette, click "Save".
At the Color Table, click OK. Save the indexed mode file with a new file name in Bitmap format. File > Save as... > enter new "Filename:" > select BMP format> click OK
BMP Options menu pop-up, choose the file format and click OK. Now you have an Index separated design saved.
Step 4 :
Open the Index separated (bitmap) file, goto Image > Mode > Color Table, the color table pop-up...
Assume that you are now going to convert BLUE color into an individual file for film output.
Leave the BLUE
color box, select & drag all the other colors, set them to complete
white (R=255, G=255, B=255), click OK, click OK again.
Click the BLUE
color box, set the color to complete Black (R=0, G=0, B=0), click
Click OK again at
the Color Table window.
Goto Image >
Mode > Gray scale > Discard color information? OK
Save the file as bitmap and name it BLUE.
Continue this "convert to Black" process for each individual color until you have all the colors saved individually in Bitmap. (This process consume less than 5 minutes)
Step 5 :
Article by : John Lean
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