There is an option to filter only one color (R,G,B,Y) in my camera. What I want to know is can this effect be achieved in photoshop? And what is this called? I tried googling monochrome and came up with nothing. My camera calls it part color.
There is an option to filter only one color (R,G,B,Y) in my camera. What I want to know is can this effect be achieved in photoshop? And what is this called? I tried googling monochrome and came up with nothing. My camera calls it part color.
This technique is called Selective color.
Sometimes, you select a point (in this case, somewhere on the CD-R case), and the region around that point that is close enough to the same color retains its color, while the rest of the picture becomes black and white.
Other times, as you mention, you can select a color and a tolerance, or a range of colors, and the software will allow anything within that range to remain colored.
On the example on the Wikipedia page, it appears that the saturated region was hand-selected or masked.
It's called Selective Color
Although masking techniques can be used to create such an image, most of the time one can use a simple Hue-Saturation-Luminance tool that is contained in many photo editing applications to accomplish very close to the same thing with a lot less effort.
Suppose I want to edit this photo to only show the blue in the sky and leave everything else B&W:
I would only need to adjust the saturation of all the other colors to zero with an HSL tool (I boosted saturation of blue and aqua while reducing the saturation of all other colors to the minimum. Reducing the luminance values for blue and aqua also caused those colors to become deeper):
But then I change my mind and want Red instead. No problem:
Or green:
Or even the pinkish/purplish color of the costumes' waists:
Notice that this last one demonstrates some "overlap" where some of the red flags in the scene have areas that are just over the line from red into magenta to leave them partially colored. To eliminate the reds one would need to either mask those parts to grey or use a tool that allows user defined widths of the specific color bands. The elementary HSL tool I'm using doesn't include such a feature, but some HSL tools do.