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by Lars Kotthoff

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12

Levels are a special case of curves, where the curve is pinned at both ends and has one control point in between. The two pairs of "input levels" and "output levels" specify the coordinates of the end points of the curve. The "middle value" specificies the degree of curvature. Levels can only have one radius of curvature, so the curve you posted is not ...


12

For the most part, it simply doesn't. The camera sets an exposure. At least in the simple case, it takes whatever amount of light is coming into the meter, and sets the exposure to make that into a fixed level somewhere in the vicinity of 18% grey. The more complex case is the multi-spot metering (goes by several names, but makes little real difference). ...


7

Provided your ISO100 image was not underexposed I wouldn't expect a noticeable reduction in noise (except maybe in the deep shadows) with the 5 1 second ISO1600 images blended together. In the infamous other thread I demonstrated that a 1/30s ISO100 will contain more noise (lower signal to noise ratio) than a 1/30s ISO1600 image. Same amount if light but ...


5

Yes, the camera has "presets" that are applied to the image to give it some more contrast, saturation, etc. It's very common for people to want to switch back to JPEG because RAW images look flat when you start out. It's important to still use RAW though, because you can add in your artistic vision a lot more effectively with more sensor data. To answer ...


5

This can be done in Lightroom (well it can in the version I use, 5). The curves tool looks like this in the Develop module: Once you've crunched your blacks using the 'Blacks' slider, you can click and drag the bottom left anchor point vertically upwards, to can make it look like this: This will lighten the blacks in the way you illustrated. You can ...


4

Think of the levels adjustment as a mathematical function; you pass in something (input), it does something to it, and returns a result (output). The input is the existing (original) value and the output is the result after the adjustment has been applied. If you open an image and apply a levels adjustment layer and look at the input sliders, first at the ...


4

This is a very nice question, but I fear that the answer is totally dependent on the performance of the sensor and its stimulus response curves. If we think of the noise as the the error between the real colour and the measured colour, we can use an statistical model to find out how many samples with greater error we must take in order to have the same ...


4

Use a curve tool. With it you can cut the levels before they reach pure black and/or white. There is a question about curves and levels for which @MattGrum posted an answer. In that answer there is images of a curve tool, and the very first of them is what you are needing. Perhaps not as agressively as in the picture, but you'll see soon enough how much you ...


4

Auto tone works by matching the lightest and darkest pixels in each channel to the pure white and pure black points in the image and clips at both ends of the histogram. However, in Lightroom, it also tries to take advantage of adaptive highlights and shadows. The first image will be heavy to the dark end of the histogram and if that end is clipped, it's ...


4

Reid. Don't throw your blacks into the pits of despair! Just don't tone so aggressively. That's the easy answer. Here's the more involved answer. I'm not sure what your end game is: print, web, tele, all have different sensitivities. But the general approach I would use goes like this. Process your RAW as you have, then hop into PS (I did my best to ...


3

You are right that curves is the way to increase detail at certain brightness levels. The steepness of the line dictates contrast (and hence detail). You only have so much "height" to play with so making the line steeper in one place (e.g. the shadows) means it must be shallower elsewhere. If you're careful you can make the line shallow in an unimportant ...


2

The answer to this is fairly complex, and is often dependent upon features and hardware specific to camera brands and models, as well as the camera exposure settings chosen by the user. To keep it simple, what the camera "sees" and what it decides to expose is dependent upon light metering. Modern cameras have sophisticated metering devices built into them ...


2

Exposure, as the name suggests, adjusts the overall exposure, just as if you had exposed the image a little more, or a little less, from the start. So if you move the exposure slider to the right, you add exposure across the entire histogram, shadows and highlights. You basically move the entire histogram to the right. With levels, you set a black, white, ...


2

When you view a RAW image, what you are actually seeing is a conversion of a RAW image. This is true whether you are looking at it on the screen on the back of your camera or on your computer screen, because the screens themselves are not designed to display more than an 8 bit per color dynamic range. Your camera, depending on model, probably records RAW ...


2

Two reasons: Because we don't see linearly and our brightness resolution sucks. Look at a gradient in 8 bit (256 grey values): http://www.tftcentral.co.uk/images/dell_2408wfp/gradient_grey.jpg We see about 16 grey patches and the two ends are most compressed for us. It's not until value 30-50 we start seeing details. So a lot of objects can be hidden or ...


2

Yes, you can replace levels with curves. I don't think there is an exact mathematical consistency in the definition of levels, but each level corresponds to a portion of the curve from left to right and will boost or drop it based on the value. I don't know that q factors are published or consistent, but normally they cover roughly 25% of the spectrum with ...


1

Because that is what they are. Effects have to be applied in an order. Input levels are adjustments to the levels that are coming in to the system. Output levels are adjustments to levels going out of the system. For example, perhaps on the input, a medium grey is actually what we want to be the darkest part of the image, so we set the input black point ...


1

To duplicate it exactly, you'd need to understand exactly what the camera does between the sensor and the finished JPEG. I'm sure Nikon knows, but I'm also sure they're not telling beyond what they cover in the owner's manual. You can, with some experimentation, approximate it. There are two major categories of changes you need to deal with: The first is ...


1

@stan rogers was correct in his comment to my original question. ViewNX provides these tools, no need to resort to paid software. From stan: select all of the pictures and apply a Picture Control then do a File→Convert Files...


1

Technically speaking, the EV of the two images is identical. You are maintaining the same exposure with both settings, the only thing that really changes is the level of noise. The amount of noise you will encounter with ISO 3200 is going to be fairly significant, and even blending all 5 images together is probably not going to produce an image with as low ...


1

The theoretical/philosophical answer would be that with each level setting you lose some information from your picture file. Camera gives you pretty much fixed dynamic range, quantized (usually) over 3x256 levels. Would the range be incredibly wider, you would have the 'interesting' parts of the picture spanned over really small number of levels (the most ...



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