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In photography creation, the picture noise affects the picture quality very much, and there are many reasons for the noise, such as high sensitivity, greatly brightening, heating of photosensitive elements, and so on, which will increase the picture noise. "noise reduction" has become one of the basic techniques that we must master.

Common noise reduction methods are ACR noise reduction, nik noise reduction, stack noise reduction, this tutorial explains the DeNoise AI intelligent noise reduction plug-in.

DeNoise AI noise reduction is a very intelligent noise reduction software, which can be used alone or installed in Photoshop as a plug-in.

If used as a separate software, drag and drop the RAW file into the adjustment, DeNoise AI will reduce the noise of the RAW file and convert it to DNG format to save.

This is Sony's RAW file, file 122.9m

This is the noise reduction export of the DNG,361.5MDNG file is the public storage format for the original data of the picture, such as Sony's ARW format, Nikon's NEF format all belong to the brand's own unique original data format, when the software converts RAW to DNG, the exported file size will be larger than the RAW file, but this does not mean that the image quality becomes better.

This is a screenshot of the RAW file.

This is a DNG screenshot after noise reduction. You will find that the exported image is darker than RAW. Even if the setting of automatic image correction is turned off in the plug-in File-preferences, there will be a dim problem, which may be due to the effect deviation produced in the translation of RAW files.

However, if we directly import the JPEG file to reduce noise, it will not produce this effect deviation, but we will not use JPEG when revising the picture.

So it is recommended to initially adjust the exposure and color bias in ACR, so that each part of the details and noise are fully reflected, and then enter Photoshop to use this plug-in to reduce noise, and then make other adjustments. Because the adjustment in ACR is lossless, this does not affect the quality of the picture.

After installing the plug-in, find it in the Photoshop filter and open it.

Apple system this software is English, win system is Chinese, so I give you translation, win system students can compare.

There are 5 noise reduction modes on the right side of the interface.

1. Standard: the most commonly used noise reduction mode is used in photos where the sensitivity is not too high and the noise is not too much, and the effect is good when the picture is relatively bright.

2. Removal: the noise reduction effect is very obvious, but it will also greatly affect the details, so it is not suitable for detailed picture content, but suitable for large area single content noise reduction, such as the overall sky, ground, desert, wall.

3. Low light: suitable for dark light pictures of the night scene, effectively reducing the noise in the dark light details. Such as night portraits and galactic landscapes.

4. High noise reduction: it is suitable for pictures with high sensitivity, which can greatly remove the noise, but also lose some picture details.

5. Lossless noise reduction: the details of the picture are well preserved, but the effect of noise reduction is relatively limited, and sometimes it can not obviously eliminate the noise, which is applicable in the case of few noise.

We can compare the effects of different noise reduction modes in the preview in the upper right corner, and then select the appropriate noise reduction mode for this image.

This is a preview of the four noise reduction modes. For this kind of portrait skin in natural light, use the standard mode. "clear mode" will significantly affect the skin color, "low light" and "high noise" will lose more picture details, as can be seen from the texture of the hair.

This is the parameter option for noise reduction, a total of 4 items.

1. Remove noise: reduce random noise, which is mainly caused by high sensitivity.

2. Sharpening: mainly adjust the sharpness of the edge outline of the object.

3. Restore the details: improve the details of the object surface obviously.

4. color noise reduction: the color noise is eliminated, which is usually caused by the heating of the photosensitive element for a long time exposure, or the dark part is greatly brightened.

Removing noise and restoring details are conflicting adjustments, eliminating noise will inevitably lose some details, and strengthening details will certainly make the noise obvious, so we need to find a balance point. Let the noise reduction degree and detail intensity in the moderate effect. If the beginner is not good at mastering this balance, just click on "automatic" in the upper right corner and let the software adjust intelligently.

This is the contrast effect before and after noise reduction.

This is the effect of using "high noise mode". The noise is very obvious after the image is 5000 sensitive and the dark part is brightened, and the noise is greatly reduced after noise reduction.

If you want to partition noise reduction, you can make a selection in PS before noise reduction, such as "color range" tool for color partition, "lightness mask" for luminance partition, or quick selection tool for content selection, or you can wipe the mask after noise reduction.

This article is from the official account of Wechat: light and Color World of Shadow Leaf (ID:wangyikai-2016). Author: shadow Leaf.

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