The old saying “A picture is worth 1000 words.” Is a great phrase when it applies to the profession of Graphic Design. When creating professional-level images, it is important to capture the moment and draw the viewer into the scene. One important aspect to this is clarity. Sometimes bad lighting, a low-light environment, technical difficulty or malfunction may cause an image to have noise, or appear to have a rough grain to it. Sometimes, a gritty, noisy image is what we are aiming for, but most of the time, we want to use clear, clean images.
Photoshop has many ways to reduce or eliminate noise and each one has its own settings. One thing to remember is that it has its limits. Sometimes, in very low-lit scenes, images will have a lot of noise. Another reason an image can have noise is when we go too far with our editing. For example, if you brighten an image too much using brightness/contrast, it can produce noise in your images and cause problems. Below is an example with some unwanted graininess in the image:
The stop sign is grainy in the image, but it should be smooth. Sometimes grain or texture is desired in an image, but for our purposes, we are going to remove it. Simply go to Filter> Noise> Reduce Noise. A dialog box will come up, giving you several options.
Your individual choices will depend on the resolution of your image, as well as the overall size of your image. For this image, I bumped the strength all the way up to 10, brought preserve details down to 0, set reduce color noise to 100, and sharpen details down to 0. Strength is for the overall strength of the noise reduction. This can create a blur effect if set too high for the image. Preserve details tries to keep artifacts and details in the image in tact. Setting this to 0 will blend color artifacts and try to create an overall flat appearance. Reduce color noise blends noise or pixilation from all three channels at one time, and sharpen details performs a low-impact sharpening effect to your image.
If you click the advanced button, you will notice two tabs appear in your dialog box. The first one is called Overall, which is the same as the normal noise reduction filter. A new area, “Per Channel” appears as the second item. Per channel gives you more control over your noise reduction choices by blending the colors in each separate channel. This is especially good if your color is solid red, green or blue, because you can select that channel, and set the strength to 10 and preserve details to 0, and you will get a smooth channel with less pixilation or grain.
Another great aspect to this is that you get a preview of each channel and this gives you a focused view, allowing you to better analyze where the graininess or pixilation is coming from within your image. This gives you pinpoint accuracy allowing you to correct channels that have noise in them, while leaving alone channels that don’t contain noise at all. The result of our adjustments are shown below:
The results are subtle, but you will have much smoother color, and less graininess or pixelation. If you want to reduce the noise of just part of your image, you can convert your image to a smart object, and then run the Reduce Noise Filter as a smart filter. This will automatically give you the option for a mask, where you can reduce the noise in an area where it is needed, while leaving other areas of the image alone.
Before Your Noise Reduction Filter:
After Your Noise Reduction Filter:
Notice that the trees are blurred and have lost a lot of detail. Convert your image to a smart object before running the Reduce Noise Filter, and you will reduce the noise in the stop sign, while preserving the detail in the trees in the background. The Best results are shown below:
You can also remove noise from your images with the Dust & Scratches Filter. This filter is very strong, with fewer settings to adjust. Go to Filter> Noise> Dust & Scratches. This dialog box only has 2 settings: Radius and Threshold. For a smoother image, set radius and threshold values close to each other, but make Threshold lower. If Threshold is set higher than Radius, then the noise will still be present in your images. It also doesn’t take a lot to get big results from the Dust & Scratches Filter. Below, you see that I set the Radius to 5 and it removed most of the noise from the image.
I used the same mask as before, masking out the tree area, so that the background isn’t blurry or distorted. The results are shown below:
Another lesser-known filter is Median. Go to Filter> Noise> Median. A dialog box will come up, but this one is extremely easy to use, because it only has one slider that controls the Radius property. It is very powerful, so you do not need much in regards to strength. I am working on a print resolution image, and 3 was strong enough to smooth out the noise in the image. Like the other filters, you are going to want to use a mask to make sure that you only affect the stop sign. If you push the Radius value up too high, the lettering starts to become distorted, which is not what we want. Finding a good balance of noise reduction, without image distortion is the main goal with each of these filters.
Here is the result of the image after the mask is applied:
Noise reduction is an integral part of image editing. You want clean, crisp images without graininess or pixilation. Sometimes this can be difficult, because of the lighting conditions at the scene, or the image quality. By using Dust & Scratches, Reduce Noise, and Median, you can quickly and easily remove noise from your images, making them look smooth and professional.