Reducing digital noise

In this exercise we are going to talk about digital noise and what you can do to…reduce its effects here inside Photoshop.…I am working in a file called Ten years younger.jpg, found inside the…exercise files folder.…Now, even this far zoomed out you may be able to see the noise inherent in this…image, but I am going to zoom in even farther into the Shadow detail in the…lower left region of this image.…Now, digital noise is random variations in the color and luminance of…neighboring pixels, and these random variations have nothing to do with the way…the scene looked in real life.…

The camera invented this noise during the capture process, so you might think of…noise as being the digital equivalent of grain in the old film days.…Now, thanks to the way that cameras capture light, noise is always going to be…most evident in the Shadow detail, and that's because the camera, in order to…convert the image to the way that we see the world, has to automatically…compress the Highlight detail and expand the Shadow detail.…