photoshop opacity.. what is it really?

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  1. #1
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    photoshop opacity.. what is it really?

    This might be suited for the photoshop forum but im not sure.. My question is.. what exactly is opacity in photoshop? I know its supposed to mean how translucent the color is.. but im confused about something. If I take a color and paint it with 50% opacity.. I can color pick that stroke and then turn it too 100% opacity and I have an entirely new color on the color palette. So basically every opacity level of every color is available on the grid where you choose a color. So in essence.. does changing the opacity change the value of the color? does it change the color itself? Something tells me its actually changing the value of the color.. since you can see that there is a location on the color picker where a stroke of low opacity is located. That sounded really confusing.. I hope you guys understand. Basically my question is.. is the opacity slider actually affecting the value of the color? if not... whatss goin on?

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  3. #2
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    I don't use opacity but I'd guess that the slider doesn't affect the colour and when you colour pick from the canvas you're colour picking the colour that's a mixture of x% brush colour and 100-x% of whatever colour happens to be beneath it.

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    its like the differnce between wood tissue paper and glass

    you can have all of them in orange, but if you overlay them over another colour some will change there appearence.

    so if you choose a red and paint it at 100% over a white it'll still be red

    turn down the opacity to 50% and youll get a more saturated(?) colour, even though in the picker its the same colour still

    pick the saturated colour, and paint that at 50% and its even more saturated, or paint it at 100% and it'll come out opaque as a solid layer of paint.

    ... saturation is the wrong word isnt it, do i mean brightness? colour terminology is f'ing confusing

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    Quote Originally Posted by Baron Impossible View Post
    I don't use opacity but I'd guess that the slider doesn't affect the colour and when you colour pick from the canvas you're colour picking the colour that's a mixture of x% brush colour and 100-x% of whatever colour happens to be beneath it.

    How do you blend without opacity?

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    Quote Originally Posted by Nrx View Post
    How do you blend without opacity?
    I use ArtRage which doesn't have opacity, the paint is always 100% opaque and the thickness determines how it blends with the paint underneath. You can 'add thinners' but it's not the same as opacity as it doesn't overlay, it behaves more like real paint.

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    Quote Originally Posted by Nrx View Post
    its like the differnce between wood tissue paper and glass

    you can have all of them in orange, but if you overlay them over another colour some will change there appearence.

    so if you choose a red and paint it at 100% over a white it'll still be red

    turn down the opacity to 50% and youll get a more saturated(?) colour, even though in the picker its the same colour still

    pick the saturated colour, and paint that at 50% and its even more saturated, or paint it at 100% and it'll come out opaque as a solid layer of paint.

    ... saturation is the wrong word isnt it, do i mean brightness? colour terminology is f'ing confusing
    It would become less saturated, I think. Saturation/intensity, correct me if I'm wrong, is the "strength" of the inherent hue (red is more red than pink, orange is more orange than brown, etc.).

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    Quote Originally Posted by Nrx View Post
    How do you blend without opacity?
    To blend in photoshop without opacity, just manually find the color in between the two colors you are trying to blend. Then paint a stroke in between the two strokes of different colors. Repeat until you have a smooth gradient of color.

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    ahh right funky,

    and i know that'd technically work without opacity, but thats not a really applicable technique is it? hard edges maybe, but to get a soft edge you'd always get those 'residue' marks

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    Quote Originally Posted by Nrx View Post
    ahh right funky,

    and i know that'd technically work without opacity, but thats not a really applicable technique is it? hard edges maybe, but to get a soft edge you'd always get those 'residue' marks
    It's certainly a viable technique with real paint. It helps you learn to see and mix colors better without having to resort to a blending brush mixing the paint on your canvas. Maybe you just need to tweak your PS brushes not to leave the marks you are talking about?

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    Having a lower opacity just means you can see more of what was under it to start with, like the tissue paper/glass thing that NRX said. It dosn't change the value (darkness/lightness) or saturation (amount of colour/grey) as those are on their own sliders.

    I would recomend just playing with it to see what a difference it makes, don't forget you can also change the opacity (seethroughness) of a whole layer in the layer pallet ^_^

    Last edited by Kitten Poker; August 7th, 2009 at 04:32 AM.
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    For the people here getting mixed up over color terminology, in the simplest terms: "value" refers to how light or dark a color is. "Hue" is the color itself. As for "saturation," think about it like this -- does your color look more like a color? Or does it look more like black/white/grey?

    So far as I can tell, lowering the opacity slider does one thing: it digitally "blends" your stroke with whatever color happens to appear behind it, with a multiplier effect determining the degree of blending based on where you set the opacity slider. Setting opacity jitter to "pen pressure" does the same thing, but dynamically increases/decreases opacity setting based on how hard you're pressing down with your pen.

    If you ask: does lowering opacity lower the value of the color? Well, that question is sort of ambiguous. The short answer is: no. Your color is still the same (look at the little color picker square if you don't believe me!) What's different is how it interacts with the colors on your canvas. If you blend your low-opacity-setting color with a very light (or even white) baclground, the new value on your canvas will be very low. If you blend your color with a very dark background (maybe even black!) the new value on your canvas will be very high!

    If you ask: does lowering opacity lower the saturation of the color? Well, that question is also sort of ambiguous. Again, the short answer is: no, your color is the same! But if you blend it with a highly saturated color, you will retain a saturated result. If you blend it with a very desaturated color, your new color mixture will still look desaturated.

    Of course, the relative value/saturation of your "blended" color depends on the value saturation of the colors you are blending! If you can't tell by now, the three elements of a color are dynamically related -- changing one of the elements may or may effect the other two -- and value/saturation can only be spoken about in relative terms, i.e. is this color *more* or *less* saturated than this other color?

    Anyway, these are all my thoughts. Somebody feel free to correct me if I got anything wrong.

    Last edited by Lamp; August 7th, 2009 at 12:50 PM.
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  14. #12
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    Quote Originally Posted by Lamp View Post
    For the people here getting mixed up over color terminology, in the simplest terms: "value" refers to how light or dark a color is. "Hue" is the color itself. As for "saturation," think about it like this -- does your color look more like a color? Or does it look more like black/white/grey?

    So far as I can tell, lowering the opacity slider does one thing: it digitally "blends" your stroke with whatever color happens to appear behind it, with a multiplier effect determining the degree of blending based on where you set the opacity slider. Setting opacity jitter to "pen pressure" does the same thing, but dynamically increases/decreases opacity setting based on how hard you're pressing down with your pen.

    If you ask: does lowering opacity lower the value of the color? Well, that question is sort of ambiguous. The short answer is: no. Your color is still the same (look at the little color picker square if you don't believe me!) What's different is how it interacts with the colors on your canvas. If you blend your low-opacity-setting color with a very light (or even white) baclground, the new value on your canvas will be very low. If you blend your color with a very dark background (maybe even black!) the new value on your canvas will be very high!

    If you ask: does lowering opacity lower the saturation of the color? Well, that question is also sort of ambiguous. Again, the short answer is: no, your color is the same! But if you blend it with a highly saturated color, you will retain a saturated result. If you blend it with a very desaturated color, your new color mixture will still look desaturated.

    Of course, the relative value/saturation of your "blended" color depends on the value saturation of the colors you are blending! If you can't tell by now, the three elements of a color are dynamically related -- changing one of the elements may or may effect the other two -- and value/saturation can only be spoken about in relative terms, i.e. is this color *more* or *less* saturated than this other color?

    Anyway, these are all my thoughts. Somebody feel free to correct me if I got anything wrong.

    now that helped a bunch! thanks so much

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  15. #13
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    I asked a question like this once, and David Briggsy told me that basically,

    PS calculates the result by mixing the RGB value of your brush with the color beneath it with the percentage of opacity.

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