It is unclear from the threads I followed how Mary Van Cline gets her photos onto glass, and whether they are fused into the glass or appliqued with an emulsion , after all, photographs were originally exposed on glass plates coated with light sensitive emulsion. The decal methods mentioned are unsuitable for fusing, unless you get a custom made ceramic decal. I have fused painted work with good success( http://www.brooksideglassworks.com/BROO ... ge_19.html
) and have silkscreened glass paint with good results also( there are several good recent threads on the topic of silkscreening).
Right now I think the best bet is good quality silk screening, prhaps combined with traditional glass painting techniques for grey areas and touch up.
Somebody will eventually adapt a large Iris type professional inkjet printer
to be able to use glass enamels or fusible powders.
One other method that has some possibilities and is cheap to explore is a kind of paper lithography which uses copier prints. Basically, you coat the
copy paper (with the photo copy image on it )with a brushcoat of liquid gum arabic. Then you apply glasspaint which has been thoroughly bended into printers oil with a brayer evenly coated with the pigmented oil. The oil sticks to the oily toner on the photocopy and not to the watery arabic. You then kind of mop up the excess ink by first squueezing some more arabic onto it and then sponging it . The photocopy image is placed inkside down on the piece of glass, covered with some absorbent paper, brayered, and then peeled back carefully. The detail possible is stunning but tonality tends to be fainter than I like. However I have not pursued it and there may be variations on the idea that would make it more effective and adaptable.