Sometimes photos get stuck to flat glass, sometimes to domed glass. Depending on the situation, it might require a professional's help in scanning if you are facing an issue with curved glass. However, if the glass (with photo stuck to it) will fit your scanner bed, place a transparency sheet down on the glass bed of your scanner. Then carefully place the glass and photo down over the transparency sheet so you don't scratch your scanner's bed. Scan at correct resolution for print size. Then carefully lift the glass and photo. Most of the time there will be problems with color, tears, cracks, or changes in surface texture. If it's a one-of-a-kind photograph, it's better to try and get a good scan before the image degrades any further. Digital editing can be done at any time. Preserving the original should be your prime motivation to scan as soon as possible.
