Cris Tambor's Library tagged fotografia → View Popular

you can also correct for color casts with Curves
Curves transforms each pixel by locating it in terms of brightness or luminosity along the bottom axis, then going up until you hit the curve line, then going across to the vertical axis to find out its new value.
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- All this still holds true when working on an individual color channel with the exception that black and white now become simply none and lots of the selected color without regard to how much of the other two color channels is present.
- If you have a green cast in the shadows, you can grab the curve on the bottom part and adjust it. If the change you want to make is in the highlights, you can move the upper part of the curve line. Or both whatever you need for adjusting the color balance. The curve for each channel can be adjusted individually.

The 1-2-3 of Photoshop Levels - Photo Tips @ Earthbound Light

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In order to avoid clipping either shadows or highlights though, we need a good way to tell where to set the black and white points.
we can use the histogram to guide us by moving black and white points to the ends of the histogram curve. Any points in the histogram to the left of the black point will surely end up black, and anything to the right of the white point will become burned out white.
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- Now for the middle, gray triangle slider. Moving it controls the overall brightness of our image without directly affecting either the highlight or the shadow end. After setting the black point and white point, the image may look a bit too dark or a bit too light. To solve this, simply adjust the gray slider to get the desired result. To lighten, move the slider left. To darken the image, move it toward the right.
- If you want to see what's going on numerically, look at the "Input Levels" values immediately above the histogram in the examples shown here. The left and right boxes show the black and white point values respectively. The central one is the gray point, but shown in terms of gamma
- A gamma of 1.0 means that the gray point has not been changed. Values less than 1.0 darken an image and values greater than 1.0 lighten it.

The Great sRGB Versus Adobe RGB Debate - Photo Tips @ Earthbound Light

So which is better? As with many things, the answer is, "it depends." You have to step back to ask "better for what?"

If you are posting images on the web, sRGB is clearly better since Adobe RGB images will likely not display correctly. But if you are sending your images to a commercial printer they will prefer Adobe RGB or even CMYK. If you are printing at home, you can generally benefit from the wider gamut of Adobe RGB as well since current desktop printers with expanded ink sets can print colors beyond sRGB.

If you shoot in jpeg, your choice of color space in-camera can be important. If you use sRGB, you will be limited to colors that can be represented in sRGB. Even if you later convert to Adobe RGB, you won't end up with colors that were never captured. If you shoot in Adobe RGB, you'll need to contend with converting to sRGB at least for posting images to the web but you'll still have a master file that has the expanded gamut for other uses. If you shoot in raw, you can defer the choice of color space until you get your images onto your computer, but you generally can't ignore it completely. Many online photo printers deal exclusively in sRGB since that is the lowest common denominator. I'm guessing they have judged that keeping things simple minimizes the customer service and support issues they have to deal with, lowering their costs. But that doesn't mean you have to let them dictate how you shoot. Just be sure to follow their rules and convert things accordingly before you send them images to print.

Working in Adobe RGB can be at least marginally more complicated since so many programs default to sRGB. If you do work in sRGB, you can often ignore at least some aspects of color management and still have images that look acceptable. Working in Adobe RGB requires you to understand more how you are interpreting color throughout your workflow. If you're a regular reader here, you know that I've tried to do my part to help spread understanding in this area. It's not really all that complicated, but it sur

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fotografia cores icc

22 Oct 08