Step 1: Open an Image on your Photoshop Canvas.
Step 2: Make a Duplicate Layer of the Background Image by selecting the Duplicate Option from the Layer Menu.
This is done for 2 reasons. First, if some step does a wrong effect then we have a backup and secondly that the Background a locked so not manipulations can be done on the Background Image.
Step 3: Now we will make the Image look like as if it is painted on a glass. To do this we will select the Glass option under the Distort sub menu in the Filter Menu.
Now we will do some manipulations in the Glass Dialog Box to get the desired effect. We will carefully adjust Distortion, Smoothness and scaling to get the proper effect. My values are shown in the figure given below. To get different type of glass effects just change the Texture option. Right Now Blocks is chosen.
Here is my image with Blocks Texture.
Now we will change the Texture option to Frosted and again carefully set the Distortion, Smoothness and scaling slider to get the proper effect.
Here is how the image will look through a frosted glass.