Uvachrome (go down the page).
Ive's also used a similar process for his Kromskop images, and if I'm not mistaken (which could be a big if), J.S. Friedman's "Dye-Toning" technique works similarly.
Here is what it says on page 340, 2nd ed. 1945, "...Mr. Miller decided that if the silver of the image is converted into silver iodide in the presence of high concentrations of potassium iodide, a completely transparent silver iodide-potassium iodide mordant is formed... When bleached in this solution, a completely invisible image composed of a complex potassium silver iodide, is formed, an image which absorbs dye..."
This works for basic dyes, like malachite green, and would definitely be image-wise.