Once Neat Image is opened, you see these tabs in the top left corner. The rest of the app is pretty much empty at this point. Click "Open input image" and select the image you'd like to denoise.

Now click on the "Device Noise Profile" tab. I rarely profile the actual photo, preferring to stick with the device noise profiles as they seem to work well for me and I find that there just aren't that many interesting photos that have large expanses of empty space to allow profiling.

In the top right corner of the application, you'll find the device profile selection box. Click the down arrow at the right of the little combo-box and you'll see menus for all the profiles you have installed. Navigate to the profile that best matches your photo ... ISO and compression amounts matter the most I think.

After selecting the profile, Neat Image will show you the noise profile that it is using. These will change if you choose to fine tune the profile. You can easily experiment with this by clicking the "Auto fine-tune" button shown at the bottom left of this panel. I never do it, but you might see some slight improvement in noise reduction performance. **update** I use auto-fine-tuning now by default. I think it allows me to back off the amount of reduction enough to retain slightly more detail.

Now you click the "Noise Filter Settings" tab at the top left.

At the top right, you'll see the filter settings. Here, I show the settings you get by default ... after clicking the reset button top right with the garbage can image on it. NI will remember your previously used settings, so once you find a set you like, you will start there every time. You can also save and restore favourite settings.

I never start with NI defaults. I first slide the "High" slider under "Noise Reduction Amounts" to the left so it reads 50%. Otherwise I find it starts to hammer fine detail too much. I also check "Very low freq" and "Smooth edges" to start with. Finally, I check all the sharpening boxes and dial the "High" slider down to about 60% to start.

Click "Preview" at the top left. Slide it around with the mouse to see the effect of changes to the sliders and check boxes. Click and hold the mouse inside the box to quickly toggle between the original and modified versions.

Once you are satisfied with the preview, select the "Output Image" tab at the top left and click "Apply" (shown here) or "Queue" (shown in the next image.)

At the top right you can choose to queue the image and let NI process images one by one as it gets to them. You can select an output image name separately, or check "Auto save output image" under "Queued Processing" and let NI create your output file names. You can set this up once and NI will remember. The, for each image, click "Queue."

NI is much faster than it used to be ... but it still takes time on a machine like mine (an older Athlon 1800+.) You can see the progress in the bar and in the application title.

If you did not queue the image, you can save the result now, assuming you like what it did. If not, just back up as far as you want and do it again.