Rick Baker
08-09-2005, 09:21 AM
http://www.rickbakerimages.com/photography_advice/reducing_noise_photoshop.html
In this tutorial, I am going to go through various methods to reduce noise with Adobe Photoshop. I'll explore Photoshop's built in tools that can be used to reduce noise as well as some third party noise reduction plug ins, Neat Image and Noise Ninja. Finally, I will show you a technique to selectively apply the noise reduction to different parts of the image, so you can get rid of the noise where you need to and preserve the details where you need to too.
First, I'm going to cover the "Reduce Noise" filter, which is new in Photoshop CS2.
I'll begin with the subject of my noise reduction efforts, a noisy image.
You can't see the noise in the image zoomed out like this. I'll double-click on the "Zoom" tool, it looks like a magnifying glass, to zoom in to 100%.
At 100% zoom level, the actual size of the image, you can see how noisy this image is.
It's time to access the "Reduce Noise" filter. I'll go to the "Filter" menu, scroll down to "Noise" and slide over and down to "Reduce Noise".
A dialog box, like below, pops up with a bunch of sliders and options.
The "Strength" slider controls the amount of noise reduction. This image has a lot of noise, so I'm going to drag the "Strength" slider almost all the way over to the right. Unfortunately, there is a trade off between noise reduction and image quality. The more you reduce noise, the more you reduce the details, so it's important to find the right balance. The "Preserve Details" slider helps to control the amount of details you want to "preserve", like the name says. Unfortunately, it can leave more noise in the image than you want. I am going to slide it all the way to the left, to preserve no details. A low "Preserve Details" setting along with a high "Strength" setting will remove the most noise.
You can see in the "Preview" area that there is much less noise than before. I'll left-click in the "Preview" area and hold down the button to see the image without the filter and let it go to return to the preview of what the image will look like with the current filter settings. There are some other controls here that aren't as important as "Strength" and "Preserve Details". "Reduce Color Noise" reduces the color noise. I'll set it at 45%. "Sharpen Details" sharpens the details. I don't want to do that, so I'll set it to 0%.
You can adjust the "Strength" individually on separate channels by selecting "Advanced", but I don't want to do that, so I won't. I'm going to click "OK" to apply the filter.
Here's the result of the "Reduce Noise" filter. It did a good job of reducing the noise, but it also reduced some of the details. Unfortunately, it's a tradeoff. Later in this tutorial, I will show you how to selectively apply the "Reduce Noise" or any other filter.
If you don't have Photoshop CS2, don't worry. There's a couple of filters included with other versions of Photoshop you can use to reduce noise. The "Dust & Scratches" filter is one of them. To access it, go to the "Filter" menu, scroll down to "Noise" and slide over and down to "Dust & Scratches".
The following dialog box will pop up. Adjust the "Radius" setting to remove noise. Usually 1 or 2 pixels is enough. If you go too far, you will really blur the image. I'm going to choose 2 pixels for the "Radius" setting and leave the "Threshold" at 0 and click "OK" to apply the filter.
This is the result of the "Dust & Scratches" filter. The noise has greatly been reduced.
There is another Photoshop filter that can be used to reduce noise called "Despeckle", it is pretty similar to "Dust & Scratches", but works on a lower level. You don't get to pick any settings, you just apply it as many times as you need to. The more you apply it, the more noise will be removed. To access it, go to the "Filter" menu, slide down to "Noise" and slide over and down to "Despeckle".
Here's the result of one application of "Despeckle" on this image.
Here's the result of two applications of "Despeckle" on this image.
Here's the result of three applications of "Despeckle" on this image. This is about enough and I think I'll stop here. The noise has been significantly reduced.
There are also third-party Photoshop plug ins that reduce noise. Many of these do a better job at reducing noise than Photoshop alone. I will briefly cover two of them, Neat Image and Noise Ninja.
I prefer to use Neat Image. It seems to do a pretty good job and it has a lot of options and features.
I have Neat Image Pro+ 5.0 installed as a Photoshop plug in. There are several versions with different prices and features. Some work as a plug in, some work as an independent program.
To access Neat Image Pro+ plug in, I go to the "Filter" menu, slide down to "Neat Image" and then slide over and click "Reduce Noise".
The following dialog box pops up. The best results come from a device noise profile for your specific digital camera or scanner. You can download these off Neat Image's web site or you can create your own. Alternatively, Neat Image can automatically build a "noise profile" by scanning the image. I want to have Neat Image do this, so I click on "Auto Profile".
I get this error message saying "Neat Image cannot find uniform area... Continue building profile?". This is because the program looks for a featureless area with only noise and this image doesn't really have any featureless areas. A featureless image is something like a sky with only noise and no real detail. Sometimes this will happen. I am just going to click on "Yes" and hope the automatically created profile will work ok.
The profile has been created. I'll click on the "Noise Filter Settings" tab to continue.
There's a bunch of sliders off to the right and more options a click a way. All of this can be pretty overwhelming.
I'm going to click on the "Preview" button to get a box where I can preview what the current settings will do.
Luckily, there a a bunch of "presets" too that make it easier on people that don't understand all the technical jargon by the sliders. I don't totally understand all of it myself. I'm going to go up to the down arrow below the "Filter Preset" field and pull down a menu and select "Remove all noise". It is pretty straightforward what this will do, it will plug in the numbers to remove all noise, like it says. The interface allow for beginners to do some basic things or a lot of control for advanced users.
I see a preview of what the settings will do in the "preview box". All of the noise has been removed and this is what I want so I'm going to click on "Apply" to apply the filter with the current settings to the image.
This is the result of Neat Image with the "Remove all noise" preset. All the noise has been removed, though I may have gone overboard and I sacrificed some of the details in the image to remove all the noise. Many times there's a tradeoff when you have a very noisy image. You have to try to find the right balance where you remove a good amount of noise, but still have good detail. I would probably go back and try and fine tune the controls better and turn down the noise removal a bit to maintain the detail. I will show you later in this tutorial how to selectively apply noise filters throughout the image.
Ok, now we'll have a look at Noise Ninja, which is another great noise reduction plug in/program. Noise Ninja also has different versions with different options. There's a Photoshop plug in version and a standalone version. I'll be using Noise Ninja 2.1.2 Pro Photoshop plug in.
To access Noise Ninja, I'll go to the "Filter" menu, slide down to "PicturePro" and over to
"Noise Ninja".
I get this dialog box, full of options.
Device noise profiles should be used to get the best results. You can download some pre-made ones for your digital camera or scanner off the Noise Ninja web site or create your own. Alternatively, you can also choose to have Noise Ninja scan your image and automatically create a noise profile. I am going to do that. I will click on the "Profile image" button under the "Profile" tab to automatically create a noise profile.
With my noise profile created, I will go to the "Filter" tab. There's a bunch of options here, but I'm mainly concerned about the "Strength" slider in the "Luminance" field. The higher the setting, the more noise is removed and vice versa.
am going to go with a "Strength" setting of 13.
I'm ready to apply the filter with these settings, so I'll click "OK".
Here's the result of filtering our image with Noise Ninja. It did a pretty good job. Most of the noise is removed, though I probably should have used a little bit higher "Strength" setting.
Now I'll show you a couple of ways to selectively apply a reduce noise filter.
One way is to create a duplicate layer of your image and apply the noise reducing filter to the top layer. Then, use the "Eraser" tool to delete parts of the image on the top layer where you don't want the noise reduction. The bottom layer without the noise reduction will show through the erased parts of the top layer.
As you can see, there's a lot of noise in the sky of this image.
I'm going to duplicate this layer by dragging the layer onto the "Create a new layer" icon in the "Layers Palette". Alternatively, I could just press Ctrl-J and it will do the same thing.
Any noise reduction filter will work for this, I'm going to use Neat Image Pro. I'll access it by going to the "Filter" menu, sliding down to "Neat Image" and then over to "Reduce Noise".
I get this dialog box. I'll click on the "Auto Profile" button near the top to automatically create a noise profile.
In this tutorial, I am going to go through various methods to reduce noise with Adobe Photoshop. I'll explore Photoshop's built in tools that can be used to reduce noise as well as some third party noise reduction plug ins, Neat Image and Noise Ninja. Finally, I will show you a technique to selectively apply the noise reduction to different parts of the image, so you can get rid of the noise where you need to and preserve the details where you need to too.
First, I'm going to cover the "Reduce Noise" filter, which is new in Photoshop CS2.
I'll begin with the subject of my noise reduction efforts, a noisy image.
You can't see the noise in the image zoomed out like this. I'll double-click on the "Zoom" tool, it looks like a magnifying glass, to zoom in to 100%.
At 100% zoom level, the actual size of the image, you can see how noisy this image is.
It's time to access the "Reduce Noise" filter. I'll go to the "Filter" menu, scroll down to "Noise" and slide over and down to "Reduce Noise".
A dialog box, like below, pops up with a bunch of sliders and options.
The "Strength" slider controls the amount of noise reduction. This image has a lot of noise, so I'm going to drag the "Strength" slider almost all the way over to the right. Unfortunately, there is a trade off between noise reduction and image quality. The more you reduce noise, the more you reduce the details, so it's important to find the right balance. The "Preserve Details" slider helps to control the amount of details you want to "preserve", like the name says. Unfortunately, it can leave more noise in the image than you want. I am going to slide it all the way to the left, to preserve no details. A low "Preserve Details" setting along with a high "Strength" setting will remove the most noise.
You can see in the "Preview" area that there is much less noise than before. I'll left-click in the "Preview" area and hold down the button to see the image without the filter and let it go to return to the preview of what the image will look like with the current filter settings. There are some other controls here that aren't as important as "Strength" and "Preserve Details". "Reduce Color Noise" reduces the color noise. I'll set it at 45%. "Sharpen Details" sharpens the details. I don't want to do that, so I'll set it to 0%.
You can adjust the "Strength" individually on separate channels by selecting "Advanced", but I don't want to do that, so I won't. I'm going to click "OK" to apply the filter.
Here's the result of the "Reduce Noise" filter. It did a good job of reducing the noise, but it also reduced some of the details. Unfortunately, it's a tradeoff. Later in this tutorial, I will show you how to selectively apply the "Reduce Noise" or any other filter.
If you don't have Photoshop CS2, don't worry. There's a couple of filters included with other versions of Photoshop you can use to reduce noise. The "Dust & Scratches" filter is one of them. To access it, go to the "Filter" menu, scroll down to "Noise" and slide over and down to "Dust & Scratches".
The following dialog box will pop up. Adjust the "Radius" setting to remove noise. Usually 1 or 2 pixels is enough. If you go too far, you will really blur the image. I'm going to choose 2 pixels for the "Radius" setting and leave the "Threshold" at 0 and click "OK" to apply the filter.
This is the result of the "Dust & Scratches" filter. The noise has greatly been reduced.
There is another Photoshop filter that can be used to reduce noise called "Despeckle", it is pretty similar to "Dust & Scratches", but works on a lower level. You don't get to pick any settings, you just apply it as many times as you need to. The more you apply it, the more noise will be removed. To access it, go to the "Filter" menu, slide down to "Noise" and slide over and down to "Despeckle".
Here's the result of one application of "Despeckle" on this image.
Here's the result of two applications of "Despeckle" on this image.
Here's the result of three applications of "Despeckle" on this image. This is about enough and I think I'll stop here. The noise has been significantly reduced.
There are also third-party Photoshop plug ins that reduce noise. Many of these do a better job at reducing noise than Photoshop alone. I will briefly cover two of them, Neat Image and Noise Ninja.
I prefer to use Neat Image. It seems to do a pretty good job and it has a lot of options and features.
I have Neat Image Pro+ 5.0 installed as a Photoshop plug in. There are several versions with different prices and features. Some work as a plug in, some work as an independent program.
To access Neat Image Pro+ plug in, I go to the "Filter" menu, slide down to "Neat Image" and then slide over and click "Reduce Noise".
The following dialog box pops up. The best results come from a device noise profile for your specific digital camera or scanner. You can download these off Neat Image's web site or you can create your own. Alternatively, Neat Image can automatically build a "noise profile" by scanning the image. I want to have Neat Image do this, so I click on "Auto Profile".
I get this error message saying "Neat Image cannot find uniform area... Continue building profile?". This is because the program looks for a featureless area with only noise and this image doesn't really have any featureless areas. A featureless image is something like a sky with only noise and no real detail. Sometimes this will happen. I am just going to click on "Yes" and hope the automatically created profile will work ok.
The profile has been created. I'll click on the "Noise Filter Settings" tab to continue.
There's a bunch of sliders off to the right and more options a click a way. All of this can be pretty overwhelming.
I'm going to click on the "Preview" button to get a box where I can preview what the current settings will do.
Luckily, there a a bunch of "presets" too that make it easier on people that don't understand all the technical jargon by the sliders. I don't totally understand all of it myself. I'm going to go up to the down arrow below the "Filter Preset" field and pull down a menu and select "Remove all noise". It is pretty straightforward what this will do, it will plug in the numbers to remove all noise, like it says. The interface allow for beginners to do some basic things or a lot of control for advanced users.
I see a preview of what the settings will do in the "preview box". All of the noise has been removed and this is what I want so I'm going to click on "Apply" to apply the filter with the current settings to the image.
This is the result of Neat Image with the "Remove all noise" preset. All the noise has been removed, though I may have gone overboard and I sacrificed some of the details in the image to remove all the noise. Many times there's a tradeoff when you have a very noisy image. You have to try to find the right balance where you remove a good amount of noise, but still have good detail. I would probably go back and try and fine tune the controls better and turn down the noise removal a bit to maintain the detail. I will show you later in this tutorial how to selectively apply noise filters throughout the image.
Ok, now we'll have a look at Noise Ninja, which is another great noise reduction plug in/program. Noise Ninja also has different versions with different options. There's a Photoshop plug in version and a standalone version. I'll be using Noise Ninja 2.1.2 Pro Photoshop plug in.
To access Noise Ninja, I'll go to the "Filter" menu, slide down to "PicturePro" and over to
"Noise Ninja".
I get this dialog box, full of options.
Device noise profiles should be used to get the best results. You can download some pre-made ones for your digital camera or scanner off the Noise Ninja web site or create your own. Alternatively, you can also choose to have Noise Ninja scan your image and automatically create a noise profile. I am going to do that. I will click on the "Profile image" button under the "Profile" tab to automatically create a noise profile.
With my noise profile created, I will go to the "Filter" tab. There's a bunch of options here, but I'm mainly concerned about the "Strength" slider in the "Luminance" field. The higher the setting, the more noise is removed and vice versa.
am going to go with a "Strength" setting of 13.
I'm ready to apply the filter with these settings, so I'll click "OK".
Here's the result of filtering our image with Noise Ninja. It did a pretty good job. Most of the noise is removed, though I probably should have used a little bit higher "Strength" setting.
Now I'll show you a couple of ways to selectively apply a reduce noise filter.
One way is to create a duplicate layer of your image and apply the noise reducing filter to the top layer. Then, use the "Eraser" tool to delete parts of the image on the top layer where you don't want the noise reduction. The bottom layer without the noise reduction will show through the erased parts of the top layer.
As you can see, there's a lot of noise in the sky of this image.
I'm going to duplicate this layer by dragging the layer onto the "Create a new layer" icon in the "Layers Palette". Alternatively, I could just press Ctrl-J and it will do the same thing.
Any noise reduction filter will work for this, I'm going to use Neat Image Pro. I'll access it by going to the "Filter" menu, sliding down to "Neat Image" and then over to "Reduce Noise".
I get this dialog box. I'll click on the "Auto Profile" button near the top to automatically create a noise profile.