ScanKromsator | СканКромсатор (Часть 5) - [102] :: Программы

daa2013

Цитата:

У меня на одном компе для оптикбука режим NONE, на другом NEUTRAL. (Драйвер почему-то работает по разному.)

Там же:

Цитата:

Color > Black point (%)
The black point marks the darkest spot of an image. A properly set black point will improve an image’s brilliance and contrast, while a careless setting will result in a loss of tonal values (since dark tonal values will be clipped). This functionality is well known from Photoshop, but VueScan has no way to set a black point via a mouse click. You must use cumbersome sliders instead.
Color > Black point (%) will set the black point for all RGB channels combined. By default, it is set to 0; sometimes setting it to a higher value can improve an image, but this depends on the image’s tonal value. Check the histogram. The curves (at least, the outer curves) should ideally start at the histogram’s left corner. In most cases, there will be a gap between the left corner of the histogram and the beginning of the curves. Change the black point settings until the curves start directly at the corner. Avoid cutting off a curve, as you will lose tonal values.

Color > Black point red/green/blue
Here you can set the black point for each color channel separately. As these values are applied directly to linear color space (not gamma corrected space), they are only available when Input > Lock image color is set. If you want to survey your changes, you have to display the histogram for the image.
You can do this with (Ctrl)-(4); the graph for the raw scan (Ctrl)-(1) is not helpful for this task. The changes will be applied at the raw level, but they will not change the RAW file itself. You basically apply the same settings here as in Color > Black point (%) ; the only difference is that you can control every channel separately. This option’s controls are difficult to handle; in most cases, you are better off not touching them and sticking to the default value of 0.

Color > White point (%)
The white point, like the black point, is generated automatically, and the default value is 1. That means 1% of the brightest pixels in the image are converted to pure white by default. In general, the effect and the handling of the white point equals Color > Black point (%) , but of course the white point affects the highlights. A properly set white point increases the contrast and brilliance of an image. An inaccurately set white point can result in clipped highlights and an overall flat look. In VueScan, there is no way to set the white point via a mouse click; you have to use the slider instead. For better control, display the image histogram. The white point is set correctly when all curves (or at least the outer curve) end at the right corner of the histogram. An empty gap is not ideal, and a curve that is clipped is worse. But there are some cases when you cannot avoid clipping completely, because you cannot move the sliders far enough.
For average daylight photos, the ideal histogram is shaped like a bell. The curves start in the left corner of the bottom line, go up, then down, and end at the right corner of the bottom line. In most cases, this type of histogram produces the best results, and it can be remembered as a rule of thumb. For exotic cases, like high-key or low-key photos, different rules may apply.

Color > White point red/green/blue
Here you can set the white point for each color channel separately. As these values are applied directly to linear color space (not gamma corrected space), they are only available when Input > Lock image color is set. If you want to survey your changes, you have to display the histogram for the image and not for the raw scan. The changes will be applied at the raw level, but they will not change the RAW file itself. You basically apply the same settings here as in Color > White point (%) ; the only difference is that you can control every channel separately.

Image graph for black and white points
With Image > Graph b/w, you can display the curves and control Color > Black point and Color > White point via triangled sliders. Reset any changes with a double click on the appropriate curve.

Модерирует : gyra, Maz
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