value or color blending mode

[einbaukueche]

coloring a greyscale image

hi there,

i am very confused about photoshops blending modes. it would be cool to have a blending mode so that the layer to wich the blending mode is applied only effects the hue and saturation of the layers below. now to me color sounded as it would do the trick, but when i checked it, by desaturating the image (on top of the color layer) it turned out also the value of the image had changed. the same thing applies if i stack a hue layer and a saturation layer on top of each othe to color an image ( only thats not really an option if you want to colorize a black and white image [pure value]).
and part of the same problem is that i can not desaturate an image without changing its value based on the saturation. now there are quiet a few ways to desaturate an image in photoshop and i would naturally try to use a HSV adjustment and just set down the saturation to zero. but it turns out, that i can only find a hue/saturation/lightness adjustment that works a little different and if i drag the saturation to zero the actual value of the pixels has changed based on the saturation. now i dont know the difference between lightniss (in the hsv adjustment) brightsnes (in my color window F6), luminosity (the blending mode) and value that i had used in other software like blender and krita. however value seems to really work independetly from the hue and saturation and in blender and krita there is a blending mode called "value" that actually only effects the value of the layers below. obviously thats equally as good as a blending mode that only effects hue and saturation as you can just put the greyscale image you want to colorize on top of your layer stack.
so i thought well i can use a greyscale image on top with the luminosity blending mode and paint the color on a layer below. but when i then desaturate the hole image to check the values, it turns out they have changed depending on the hue and saturation i used on the lower layer. this would not happen with a "value" blending mode.

i don`t get it. photoshop is a pretty intuitive software, really easy to use, you don`t need to learn anything, you can just work with it usually, but when blending value and color i dont see the logic.

thank you for your attention and i would be happy if you could tell me i just have to change some setting. also a theoretical explenation would be interesting.

 

[Tom Mann]

Sorry, but I am just about to leave on a several day trip, so, unfortunately, my reply has to be terse.

If you want a good intro to the differences between the various three component color spaces, study, not skim:
http://en.wikipedia.org/wiki/HSL_and_HSV
http://en.wikipedia.org/wiki/Lab_color_space
...pay particular attention to the disadvantages of HSL and HSV representations of a color.


...and for a nice long list of many of the huge number of other color spaces:
http://en.wikipedia.org/wiki/List_of_color_spaces_and_their_uses .

With respect to your particular request for tools which rely on "value", realize that Adobe went away from this for a reason.

So, instead, I would ask you to consider for a moment the operations you would like in "Lab" space instead of in HSV. So, for example, if you want to desaturate an image, just set a=b=0, etc. etc.

Sorry, got to run.

I'm sure some of the other folks will chime in here with their thoughts on this subject.

Tom M

 

[einbaukueche]

ok, thank you very much for the helpfull links. i should be able to find the wikipedia site myself, but sometimes if you don`t know what to look for... so thank you i think i ruffly understood that L*a*b* is pretty fancy. in my case i tried to lern something about painting or creating images in general by breaking down the the color into two aspects, its "value" and its actual "color" information. So i wanted to paint an image in black and white first and later colorize it, so i could focus on one problem at a time. now the different color spaces introduce interesting optios. from what i`ve understood, the L*a*b* color space fits the human perception of brightness or what i used to call "value" in general (not technical) a lot better and so i guess painting a black an white image with it`s value representing the actual Luminosity* of the final image might be closer to how a traditional painter looked at his painting, because in the and the compostion should probably be about the percieved value not about a theoreticle variable V used to define a color in a digital enviroment.
how ever choosing a color with the L*a*b* sliders isn`t intuitive at all and i much prefer picking a color from a color wheel with a seperate value slider by the side. so when painting directly in color this seems to be very practicle.
In this case, where i decided to paint the percieved value first i will try to change the image> mode> Lab Color and than have the painted greyscale layer set to Luminosity blending mode on top and then paint color underneath. because its more intuitive i will still choose the colors with the old HSV method, see how it looks with it`s modified Luminosity and then mix the colors on the canvas as i go. it get`s a little more complicated then i expected but it will be a nice experiment. maybe in the long run painting in HSV choosen colors but the checking for the luminosity is indeed a strategy.
Thank you, it makes more sense to me now.