photo fused in glass

Can someone tell me how people are fusing so many beautiful pictures in glass??? I saw a plate with a violet picture fused in the center and the lady said she took the picture--but would not discuss how she did the plate.  I have seen several jewelry pendants with flowers, children, dogs and whatever.  I have tried the paper and printer--but these pictures are colored and great looking.  I have used decals on glass too.  One lady did tell me she had to put the clear liquid glass on first and then fire.  Is this just a clear coat paint and did not really fired in the glass?