Reduce noise area Lightroom Total Mastery

use Ctrl+5 (mac:command+5) to open the detail panel. The detail panel is divided into three sections from top to bottom, with a square navigation pane at the top. Click inside the pane to toggle between the fit and 100% magnified views, or you can right-click (mac:control+ click) in the window to enlarge to 200%. As I told you, in the detail panel you usually need to use the 100% magnification view to carefully observe the details of the photos, so Lightroom forces you to provide a larger preview view inside the detail panel. Below the Navigation pane is the sharpening area, and at the bottom of the panel is reducing the noise area, which is what we're talking about here.

The detail panel is divided into navigation panes, sharpening, and reducing noise in three areas. Clicking the button in the upper-left corner (the red circle) allows you to select the area you want to enlarge directly on the screen to display in the Navigation Pane. The Navigation Pane has a small black triangle to the right, and clicking the small triangle closes the navigation window.

If you prefer to use the Navigation Pane in the details panel, you can select an observation area by dragging the screen directly in the Navigation Pane. Alternatively, you can activate the selection tool by clicking the button in the upper-left corner of the Navigation Pane and select the appropriate area with your mouse across the photo. Once you have selected the area, you can secure the current area to the Navigation Pane by simply clicking the mouse. I personally think that the better way to look at details is to enlarge the photo directly to 100% or more, so that you will have a preview area much larger than the narrow navigation Pane in the Detail panel, and more appropriate to see the larger area.

The main window (red box) is obviously a better preview than the preview pane (yellow box) in the detail panel. Zooming in to 100% or greater is the best way to observe the effects of noise reduction and sharpening.

Default parameters for noise reduction

The noise reduction area is further divided into two regions, the above is the brightness noise-reducing area, the lower is the color noise area. No matter what type of file you open, the Brightness command defaults to 0, but the default value for the color command is not necessarily 0. When you open JPEG, TIFF, PSD and other files, the default value of color denoising is also 0, however, if you use raw files, you will find Lightroom default color command value is 25. In other words, Lightroom defaults to apply a certain degree of color noise reduction to all raw files.

I don't know why Lightroom set the default color noise value to 25, I guess it's probably a balanced consideration. As we discussed in the previous section, digital photos require the best balance between signal and noise, and any signal recording will be accompanied by noise, only the difference between signal-to-noise ratio. Setting a certain color noise reduction will probably get a greater latitude for most photos, without damaging details and making most photos look cleaner.

However, sometimes the 25 setting seems to be unnecessary. In particular, you don't need any color noise when you're using the camera's base sensitivity to take a very accurate picture in good light. So I suggest that you set the value of the color command to 0 when dealing with raw photos, and then make adjustments as needed.

The image above is a raw photo taken using base sensitivity, which sets the color noise to 0 (turn off the color noise), and it is hard to see the color noise even in a very dark place (red circle) when magnified to 100%. Therefore, it is not necessary to use the color noise reduction command for such a photograph.

Remove color noise from a photo

The color noise is expressed as a red, green, or blue noise point. The effect of color noise on the appearance of the photo is very obvious, so we should pay more attention to the color noise than the brightness noise. Unless the noise of the photo is very obvious (as we see in Figure 13-8), in most cases the color noise can be solved relatively well. After removing the color noise, the details of the photos are usually not affected significantly.

The color denoising operation is very simple, moving the color slider to the right will increase the intensity of the color noise reduction. A good way to use the noise Reduction command is to activate the color command Value box, use ↑ or ↓ to adjust the value, and observe the effect. If you want to adjust the value quickly, you can use either shift+↑ or shift+↓. In most cases, the value of the color noise reduction command does not need to be set very high, or even basically does not need to exceed the Lightroom default value of 25. The setting principle of color noise reduction is to use the minimum value that can remove the color noise. Even for high noise photos, the use of lower color noise settings can also be a good way to remove the color noise.

Using the color noise reduction command can significantly reduce the color noise on the photo. Sets the color command to be able to remove the minimum value of the color noise, which is typically less than the default value of Lightroom 25. Here the command value is set to 15, in 200% of the view has not seen the obvious color noise before the noise reduction, improve the parameters do not get better noise reduction effect.

Even if the noise is so obvious, using Lightroom's default color noise setting, no color noise can be seen in the 200% view.

Although the effect of color denoising on photos is often not obvious, it does not mean that the color noise reduction has no negative effect on the photo. Color noise can also affect the details of the photo, especially the color details. If you set the color noise reduction command very high, the photo color will be offset, and even appear color artifacts. The details command below the color command enables you to fine-tune the color noise reduction commands. The detail command controls the color noise threshold and moves the detail slider to the right to retain more color details, but it may make the noise point obvious; moving the detail slider to the left enhances the noise reduction effect, but the effect on the color of the photo is more pronounced. The details command needs to be set according to the actual picture, unless the color noise of the photo is very obvious, otherwise you can put the detail command on the default value many times.

Color noise reduction commands can affect color. In this example, if you set the color noise reduction command to 100, the color saturation is significantly lower than the photo before the change. This is a common case where color noise has an effect on color details. In other cases, color denoising can affect the color transition and form unnatural artifacts.

Also use the default color noise setting of 25, the detail command on the left is set to 0, the right image is set to 100, and the detail command can be clearly seen to affect the color details. Increasing the detail setting value helps preserve the color details, but it also brings back the faded color noise.

Reduce the brightness noise of the photo

If you are careful enough, you will find that in the section on color noise, I name the title "Remove the color noise of the photo", and here I'll name the title "Reduce the brightness noise of the photo." To eliminate the effect of noise on photos will always affect the details of the photos, so we say "noise reduction" rather than "remove noise." The color Noise reduction command has a relatively small impact on the details of the photo, and we may be able to approximate it to "remove" the noise, while the effect of the luminance Noise Reduction command on the details of the photo is obvious. At the same time, reducing the brightness of the noise is very difficult, you must clearly realize that you are only "reduce" noise and can not fundamentally "remove" noise.

The brightness noise is visually manifested as the visible particles on the screen. When the color noise is removed, the remaining monochrome particles are the brightness noise. Moving the brightness command to the right can reduce the image's particle sense and play a role in reducing the luminance noise. However, the brightness noise reduction has the extremely strong side effect. Brightness noise reduction is the cost of the loss of detail. In order to blur these photo particles, Lightroom will blur the photo according to the Set brightness noise reduction value. As the noise fades away, the details on the screen disappear.

Change the value of the brightness command when other conditions are unchanged, and the three graphs represent the luminance noise reduction setting of 0, 40, and 100 respectively. When the noise intensity increases, the detail loss becomes apparent. When the noise reduction is set to 100, although the screen is very clean, all the noise has disappeared, but the details of the screen has been lost, the details of the fluff has been simply unrecognizable, but blurred into a lump of color.

If you're taking a JPEG photo, especially if you use very high sensitivity to take photos, and the camera you use is a small DC that claims to make the night as bright as daylight, zoom in to 100%, and you'll see that these photos are similar to what you get in Lightroom with a very strong brightness noise. The physical principle of the sexual noise ratio cannot be broken, so in the brightness noise you need to consider how to strike a relatively reasonable balance between the noise and the details, depending on your own tolerance of noise, and also on the final output of the photo.

When the brightness noise on the photo is not obvious or relatively weak, it is not necessary to apply the luminance noise reduction command to remove these noises, because the effect on the details may be better than the benefits of noise reduction. Especially on the screen to see or print a smaller size of the photos, these noises will not have a real impact on the photo, so you can be relatively tolerant of some. And if the image of noise is obvious, then have to use the Brightness noise Reduction command for certain processing. Below the brightness command there are two sliders for detail and contrast, and these two commands are designed to fine-tune the effect of the brightness noise reduction, and are mainly used for very obvious images of noise. Moving the two command sliders to the right helps preserve the details, but may increase the noise, while moving the two sliders to the left will enhance the effect of noise reduction, but also further damage the details of the photo. In the noisy photo, try these slider combinations constantly to get a relatively good result.

We have seen the situation before, using basic speed shooting, but the exposure is seriously inadequate. After applying the color noise reduction, some brightness noise is left on the screen, especially in the shaded area (arrow). The details of the photo body area are preserved well, when we can not reduce the brightness, or apply a lighter noise reduction (such as setting the Brightness command to 10~20), it is more important to keep the details than to remove the noise points.

The detail command controls the noise threshold, and the higher the detail setting, the Lightroom will tend to retain more detail while increasing the latitude for noise, while the lower the detail setting is the opposite. On the premise of keeping the other conditions unchanged, the picture on the left is the performance of the detail set to 0 o'clock, while the right figure is the detail set to 100, the right figure is significantly more granular than the left, and note that some of the blurry details in the left image (such as the bridge that the Arrow refers to) can retain a better edge in the right picture.

In the diagram, the left is the case where the contrast is set to 0, and the right is the contrast set to 100. The contrast command can be used to enhance the noise reduction effect or highlight the details by controlling the gray-level contrast. Although increasing the contrast may help preserve the edges, you can see some unnatural edge transitions in the right image. Contrast commands are often used for images where noise is too obvious, and a relative ideal balance is obtained between edges and noises according to the actual situation.

After the brightness noise reduction, usually the picture will always appear very unclear and blurred. At this point, we need to use the sharpening command to retrieve some of the missing photo details.

Category:

• PS Image Processing