But it will still only have the same local contrast between dark and light areas. After sharpening the edge will be narrower and thus steeper, and maybe only extend over two or thee pixels width. frequency based sharpen filters will even decrease the global contrast.įor example, if you have a blurred image with a dark object on a light background, the edge may extend over 5 pixels width because of the blur, and vary slowly from dark to light. Sharpening will locally increase the steepness (gradient) of edges - the rate at which the intensity will vary from light to dark, but the overall contrasts should locally remain the same. You use the Definition Quick Brush adjustment to add clarity and reduce haze without adding too much contrast to the area of the image the adjustment is brushed on. By Apple's own description in the manual: This will make the colours more vibrant but preserve the local contrast. "Definition" does an intensity remapping, but it is mainly shifting the intensities by subtracting locally an equal amount of "whiteness". Viewed this way, many adjustments, that are intensity remappings, are only accidentally contrast adjustments and I would not lump them into this category. I use the term "contrast" to describe the local or global difference in intensity or color, and would reserve "contrast change" for adjustments, that are intended to (and will) spread or lower this difference - locally or globally. That will depend on your definition of contrast, Frank 😀 your usage of this term is more general or all-embracing then the way I like to use it. It's where on the image that the contrast is being manipulated that changes. I don't swear to the exactitude of the following, but fwiw, I think of capture sharpening as what needs to be done to prepare a digital negative for editing I use aesthetic sharpening to guide the eye of the viewer and I apply whatever output sharpening is advised in order to _retain_ the look of the edited Image when I publish it as a digital file.Ĭontrast, definition and sharpening all deal with contrast. Output sharpening should be device-dependent: sharpening for a JPG destined for the Web will be different from sharpening done to a TIFF being sent to a printer. Aesthetic sharpening is whatever you want it to be. The other sharpening tools in Aperture are used for "aesthetic sharpening" (a/k/a "artistic sharpening", a/k/a "creative sharpening") and "output sharpening".
The sharpening in the RAW Fine Tuning adjustment is, procedurally, "capture sharpening".
I suggest starting with this short primer: Sharpening digital camera images is a complex topic.
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