Abstract: A process for producing and fixing an image uses an imaging medium comprising an acid-generating layer or phase comprising a mixture of a superacid precursor, a sensitizer and a secondary acid generator, and a color-change layer comprising an image dye. The sensitizer can absorb radiation of a sensitizer wavelength which does not, in the absence of the sensitizer, cause decomposition of the superacid precursor to form the corresponding superacid. The secondary acid generator is capable of acid-catalyzed thermal decomposition by the first acid to form a second acid, and the image dye undergoes a color change upon contact with the second acid. The medium is imagewise exposed to radiation of the sensitizer wavelength, thereby causing the sensitizer, in exposed areas, to decompose superacid precursor with formation of the fist acid. The medium is then heated to cause, in the exposed areas, acid-catalyzed thermal decomposition of the secondary acid generator and formation of the second acid.

Abstract: The addition, to a thermal imaging medium comprising a color-forming compound which undergoes a change of color upon heating above a color-forming temperature for a color-forming time, the color-forming compound being of the cyclic sulfonamide type described in U.S. Pat. Nos. 4,720,449 and 4,960,901, of a quinone or hydroquinone increases the sensitivity of the imaging medium and helps to prevent fading of images produced therefrom while the images are being projected.

Abstract: The addition, to a thermal imaging medium comprising a color-forming compound which undergoes a change of color upon heating above a color-forming temperature for a color-forming time, the color-formingcompound being of the cyclic sulfonamide type described in U.S. Pat. Nos. 4,720,449 and 4,960,901,of a source of zinc, nickel, copper(II), cobalt(II) or aluminum(III) cations increases the sensitivity of the imaging medium and helps to prevent fading of images produced therefrom while the images are being projected.