New answers tagged image-processing
In USM (unsharp masking) radius is not the size of the kernel, but related to sigma. A good rule of thumb is that actually visible radius of the effect is close to radius * 3.3. So USM with the "radius" of 0.3 is pixel-level sharpening.
Sharpening at that level is usually done with a deconvolution sharpener, such as the Smart Sharpen filter in Photoshop/Elements (or at higher radii, using a plugin like Topaz Labs InFocus). Unlike the usual sharpening tools like Unsharp Mask, which are just edge/contrast enhancers, deconvolution sharpeners attempt to compute what the data would have looked ...
Cycles/distance is half the value of pixels/distance, but the usage is somewhat different. Pixels/distance is commonly used to specify how close sensors are on a digital sensor, while cycles/distance is used to specify the actual ability for the sensor to reproduce an image. Also, cycles/distance can be used for non-digital processes where there are no ...
DxO 9 has a new PRIME algorithm that is marketed as being a very much improved noise reduction algorithm for high ISO images. Here is a link to start you off on the PRIME algorithm. PRIME by DxO I have used it myself and I am happy and quite impressed by the result. But it is very processor intensive and takes a long time to process each image.
Denoising is a vast subject, there are a lot of methods and a lot of research papers about it in the literature. A simple and efficient algorithm that you can take a look at is called Non Local Means. Basically it aims at averaging pixels that look similar as there are a lot of redundancy in an image. You can do it on the bayer (by taking into account the ...
Brightening gamma in Luminance channel tend to change the perception of colour. Satuaration seems to increase, particularly yellow, since yellow maxes out luminance next to white. Left column: RGB Right column: Y in YUV Top: brightening gamma Bottom: darkening gamma. I think RGB gamma is more pleasing/intuitive when brightening and Y gamma when ...
Consider Capture Raw data--> white balance --> gamma --> De-Bayer(Get RGB)
Check out RawTherapee's LMMSE demosaicing algorithm- it's designed for noisy images, and offers options on noise reduction.
GIMP has an extension called MathMap that can do this, too.
If you wait until late in the process to change camera profiles, what Adobe is really doing is going back, converting the RAW image using the newly selected profile, and then applying all of the adjustments to the newly created image (using the new profile) that you had made to the older image created from the same RAW file using the previous camera profile. ...
The profiles are necessary in the conversion process in order to make the colors look "correct". There are multiple profiles to choose from (and user can make additional ones) in Lightroom, because sometimes more accurate rendering is needed and sometimes more pleasant rendering is preferred. And some profiles are designed to match picture styles of the ...
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