Abstract: Reduction and gold fogged Lippmann emulsions are described wherein the emulsion is fogged with from 0.07 to 0.5 milliequivalents of reduction fogging agent and from 0.01 to 0.1 millimole of gold fogging agent per mole of silver halide and the emulsion comprises more than 2 g and at most 10 g of electron acceptor(s) per mole of silver halide.

Abstract: A method of producing direct-positive images is provided which comprises developing an exposed direct-positive silver halide emulsion comprising electron-traps and fogged silver halide grains in the absence of halide ions so as to obtain higher maximum density. It is possible to decrease the degree of fogging so as to obtain direct-positive emulsions of high-sensitivity which, when developed in the absence of halide ions, still provide favorable maximum density values.

Abstract: Direct positive silver halide emulsions are provided which contain fogged silver halide grains with a layered grain structure wherein the external shell of the silver halide grains comprise up to 20 mole % of silver iodide based on the silver halide of the shell. The emulsions show improved sensitivity and produce images of improved maximum density.

Abstract: In the preparation of silver halide emulsions silver halide grain-growth is accelerated by the addition to the precipitation medium during or before silver halide precipitation of a compound of the formula ##STR1## wherein: N IS AN INTEGER FROM 1 TO 5R.sup.1 is C.sub.1 -C.sub.5 alkyl or substituted alkylR.sup.2 is hydrogen or C.sub.1 -C.sub.5 alkyl or substituted alkyl, or a carboxylic acyl groupR.sup.3 is hydrogen or C.sub.1 -C.sub.5 alkyl or substituted alkyl, andR.sup.4 is hydrogen or C.sub.1 -C.sub.5 alkyl or substituted alkyl group, aryl or substituted aryl or a salt-forming cation.

Abstract: Direct positive silver halide emulsions are provided which contain fogged homodisperse silver halide grains having a silver iodide content of more than 10 mole % and at most 20 mole % relative to the total amount of silver halide. These emulsions have higher sensitivity than corresponding fogged emulsions with less silver iodide content.

Abstract: Direct-positive emulsions are described comprising incorporated developing agents wherein the developing agents are 1,4-dihydroxybenzene compounds of which at least one of the hydroxyl groups has been esterified to form a hydrolyzable aliphatic acyloxy group comprising a quaternary ammonium group.

Abstract: A method is described of preparing a blend of direct-positive silver halide emulsions that has a pAg value of at least 8.35 from two or more direct-positive silver halide emulsions of different average grain-sizes comprising fogged silver halide grains and having pAg values below 8.35, without inducing physical ripening, by raising the pAg to the value of at least 8.35 before or after blending the emulsions, and providing at least one electron-accepting or halogen-conducting compound, at the surface of the fogged silver halide grains prior to raising the pAg to the value of at least 8.35.

Abstract: Reduction and gold fogged direct-positive Lippmann-emulsions have improved gradation and higher maximum density when fogging occurs in the presence of a palladium compound.

Abstract: Direct-positive silver halide emulsions comprising fogged silver halide grains and an electron acceptor are described wherein the emulsion is spectrally sensitized by means of 2-aryl-indolocarbocyanines. The combination of electron acceptors and these spectral sensitizers provides super-sensitizing effects that are not impaired by the presence of color couplers.

Abstract: Direct-positive silver halide emulsions are described which have been fogged so that a test portion thereof when coated at a coverage of 0.50 to 5.50 g of silver per sq.m. gives a density below 0.50 upon processing without exposure for 6 min. at 20.degree.C in a developer I and an identical coated test portion gives a density that is at least twice that of the first test portion with a minimum of 0.50 upon processing without exposure for 3 min. at 20.degree.C in a developer II.The emulsions have high photographic speed and though fogged to a very low degree can yield direct-positive images of satisfactory density.

Abstract: Direct-positive silver halide emulsions comprising fogged silver halide grains and having adsorbed to the surface of said grains an electron-acceptor have improved stability and speed when subsequent to fogging of said grains and addition of the said electron-acceptor the pH of the emulsion is lowered, preferably below pH 6.