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8

Yes, your assumption is correct. A levels control is basically the equivalent of a curves control that can only be adjusted at the end points and one point in the middle, while a contrast slider is (usually) the equivalent of moving both ends at the same time (although some may be more sophisticated). The curves tool gives the most flexibility, but also ...


7

Just perform regular post-processing. For reference, here is your first picture with all the boarder fluff stripped off: Simply making the darkest spot black and the lightest white fixes a lot: The snow looks a little yellowish, so here I'm using one area of the snow that looks like it should be white as the white balance reference. I also brought the ...


4

I look at them kind of like sandpaper for a woodworking project: The Contrast slider is the really coarse paper that you use to get in the ballpark of the final shape you want, the Levels sliders are like a medium grit that allows you to fine tune the shape and get closer to your goal, and then the Curves allow the finest control like a really fine grain ...


3

What your colleague meant, based on your description, was: Setting the white and black point of the image. On an 8-bit grayscale image, you have 256 different values ranging from total black (0) to total white (255) and various shades of gray (values 1-254). An image with content only in the ranges between e.g. 0 and 120 (under exposure) might feature "...


3

Hum. You can not do some transformations with curves alone if your image is on RGB mode. All depends on what information you have on each channel. Here is a simmilar question: What's the best method to change colours in a photo to another specific color? asking color changes using curves or levels. You can not "desaturate" a color image using curves ...


3

You say: I suppose that all the transformation we can make to an image which operate on one pixel per time (for example levels, saturation, color balance) can just be done with curves. This is not correct. Some examples include converting to monochrome, making the image sepia toned, or even your example of changing the saturation. Increasing the ...


3

Although the color information loss is clearly not avoidable in this kind of 8-bit transformation, you can have a better behaving image if you accept a bit of a loss in sharpness... I do not know in other programs, but in darktable you can use t he module "dithering": I tried the same trick on a small jpeg image, and this is the result: before: and ...


2

A few years late, but I think it contributes. The Curve Tool can directly do anything that the Levels tool can do. And a bit more too, but the curly curved "curve" part is simply one option, but the Curve tool has several other features which directly match Levels. The Curve Tool is perhaps more graphical than Levels, but both show the histogram background. ...


2

The basic answer is that you can only modify with curves (do not use levels) If and only if you do have the primary color component on the mix, and you can only shift the colors to some degree. You can not in this case: Here is an example image with some clear colors. I separated the channels and you can see for example that I only have information on the ...


2

Habits (or compatibility with a legacy of thousands of Youtube tutorials out there...). Actually what would make sense is a 0.0->1.0 scale or percent values (with fractional part). These values are the same with all data representations (8-16-32 bit integer, and 16-32 bit floating-point). Which, by the way, is what Gimp has switched to since it started ...


2

16-bit is only used for internal calculations. What you actually see on your monitor is in 8-bit. Since an 8-bit monitor can only display 256 levels (0-255) and is unable to display the difference between two 16-bit values that are both converted to the same 8-bit value, the GUI uses the 8-bit values. (Even if you are using a 10-bit monitor and graphics card,...


2

LR uses ProPhoto with a gamma of 1 for calculations, but it uses a gamma of 2.2 for the interface (histogram, tone curve). Photoshop uses whatever gamma is correct for the chosen color space (2.2 sRGB, 1.8 ProPhoto)... but none of that really matters and it's not what is causing your issue. Your issue is that the RGB numbers mean different things in ...


1

Notice that the tone curve is set to represent light... it doesn't matter if the image is grey scale or color. In color the 0-255 value of each channel represents the brightness of the tone (i.e. Red, Green, or Blue). When you make the curve adjustment of 70 to 137 it is not simply changing the number... it is changing the relative value of 70 to a new ...


1

At best you can only makes guesses because you'll have no way to know if it was only one curve applied to the entire image. For example when I'm working on nearly any photo I almost always have a folder structure that includes: Local Adjustments Global Adjustments Anything that I intend to have on the entire image I put in my global adjustments group. ...


1

RGB is fine for minor changes such as going from blue to cyan, but if you want to make major changes you should learn how to work in LAB. LAB's separation of color from luminosity into two distinct opposing channels makes it easy to change one color into any other color using a combination of channel blending and curves. For example, I was able to change ...


1

You can't, easily, because hues other than pure red, green, or blue are made of mixes of those colors. If you want to increase or decrease the proportion of one of these in a constant way, the levels tool will work. If you want to increase or it only in highlights or shadows, or in an area that's got a particular cluster of a certain brightness of that ...


1

You should apply the LUT to each channel. If you are really interested in image processing theory, then you should start a new question asking for book recommendations on the subject, if it hasn't already been asked.


1

For next time, you might want to take a closer look at your manual to figure out how to improve capture. Snow throws off most auto camera settings, and many cameras now have an automatic snow/beach mode to adjust (or at least an exposure adjustment setting), but if you understand what's going on even the basic adjustments available on your camera can be ...


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