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I have a photo and I scanned it, but the scanned version introduced a lot of white spots on the image. I think the problem is the type of paper of the photo, which is not smooth a bit rough. There's something I can do? some technique to scan it? or post processing it? I tried a denoiser filter which didn't make any difference.
This is just part of the original image scanned at 2400dpi
Please view at 100%
at 100%
The picture itself it is ok.
Viewed in a angle
If you have the negative, you will have better luck scanning it. The issue is (as you are guessing) with the non-glossy finish reflecting the bright light from the scanner.
If you do not have the negatives, scanning the photo in different orientations may help as this will change the direction of the reflected light.
Finally, you can also try the rotation approach to create two different scans and then overlay in photoshop and then try a darken blend mode. This works well, but takes a lot more effort.
Sometimes scanning software will have a dust/crack/hair/speckle removal tool that might do a better job with this particular type of issue. Noise reduction is more concerned on averaging to reduce image noise that appears evenly through an image. Despeckling looks for small dots that don't fit with their surrounding area and is the appropriate filter for this kind of problem.
By far the easiest answer is to use photo editing SW. I used Adobe photoshop. "Filter" --> "Noise" --> "Dust & Scratches...". Took it right out.
A trick i have done to get around this is if you can find very thin, and almost see through tissue paper and put it in front of the picture as you scan it, it will cause a haze or a overexposure on the type of tissue paper but it will remove any gloss and reflection from the scanner. might even remove the white spots if that is reflecting the light. afterwards, you may have to do some Photoshop work to adjust the the picture to proper exposure but it should work for you.
this is if you are using a printer/scanner/copier system or a scanner with a lid, if you are using a open ended scanners (yeah they exist) use a book or something solid white or solid black to trick the scanner into being a closed scanner and you should theoretically get the same results.
It appears that you have a glossy surface with a pebbled texture. Each small bump has an individual specular reflection, a highlight.
Rescan the photo with a high-count mega-pixel camera straight-on with the illumination at an angle to the photo to minimize the glare from the uneven glossy surface. (Remember that a camera is a portable scanner behind a lens without the light source.)
Purchase an aerosol can of dulling spray at an art supply store and dust the surface enough to remove the highlights. Let it dry completely. Use the absolute minimum to do the job. This is one-way for your print. (There are removable types that are made specifically for scanning film negatives and photographic materials; but, they are difficult to find, now.) Normal removable dulling spray doesn't dry completely and will take some care to remove completely.
