How to change black on white eps to blue on white?

I have an eps which is black on white.

In Photoshop, what's the easiest way to create a version which is blue on white?

I've done it by converting to Duotone, but that seems a bit long-winded.

Apologies if this is answered elsewhere, but I couldn't find it in the forums or documentation.

Sam Dutton

Sam,

if it´s already raster graphic:

Mode RGB
Hue/Saturation
Colorize (bottom right in PhS7 H/S menue)
Adjust e.g. H=240, S=1, L=1 (fully saturated blue)

If it´s vector graphic then don´t use PhS. The result will be rastered. Illustrator should work.

Or a simple text editor (WordPad). Replace color settings by r g b setrgbcolor
e.g.
0 0 1 setrgbcolor

Grayscale: replace
g setgray

RGB: replace
r g b setrgbcolor

CMYK: replace
c m y k setcmykcolor

All numbers g, r,g,b, c,m,y,k are in the range 0.0 .. 1.0. There are some other color spaces. Then it´s not as simple.

Save as plain text as *.eps.

Best regards --GernotHoffmann

Thanks Gernot -- comprehensive!

I'll give both methods a try. (Obviously, opening the vector graphic in Illustrator is a sensible option -- I just don't have it installed here. In fact, I was trying to help another user working with The Gimp.)

Sam

Gernot

One other question...

I used your Hue/Saturation > Colorize method, but when I set the HSB values to the equivalent of the RGB colour I want (219, 100, 84 for #004AD5) I get a different, paler blue.

Any idea what's going on?

Sam

Sam,

first a strange observation: the Lightness scale in Hue/Saturation is not the same as Brightness in HSB. But maybe an adjustment by appearance is sufficient here.

Your values RGB are a desaturated red (wrong order BGR instead of RGB ? ), and your hex values don´t match.
We can forget the hex numbers and consider only RGB versus HSB for blue:

Imagine a color cube RGB:
1. For all values R=0,G=0,B=0..255 we´ll get fully saturated blue from dark blue (black) to vibrant blue.
2. The blue is desaturated if we add white by EQUAL amounts of the two other colors:
R=0..255, G=0..255, B=255
The end point of this path is white.

The same path in HSB: 1 means 100%
1. H=240, S=1, B=0..1
2. H=240, S=1..0, B=1

Of course any other path is possible.

For an illustration one may want a blue like this:
H=240, S=0.5, B=1 (not explicitly tested, depends on the rest of the graphic).

Fully saturated blues are not printable, by the way.

Hope this helps for further experiments.

Best regards --Gernot Hoffmann

Thanks again, Gernot.

The numbers I gave were for the (hex) value 004AD5 which, when entered in the Photoshop color picker gives 219, 100, 84 for HSB. In decimal that means R = 0, G = 74, B = 213, doesn't it?

Sam

Sam,

I see, the numbers 219 .. are for HSB; but the hex values are always for RGB. They are quite useless, with the excep- tion of stone-age HTML.

Best regards --Gernot Hoffmann

They are quite useless, with the excep- tion of stone-age HTML

:-)