Abstract: A high-contrast direct positive prefogged silver halide emulsion free from coror stain, which contains at least one new dimethinecyanine dye wherein the 3-position of a pyrazolo[1,5-a]pyridine nucleus is bonded through a dimethine chain to the 1-, 2-, 3- or 4-position of a cyanine hetero ring nucleus, provided that where the bonding is in the 4-position said cyanine nucleus is a quinoline nucleus or a pyridine nucleus and where the bonding is in the 1- or 3-position said cyanine nucleus is an isoquinoline nucleus, said dimethyinecyanine dye being present in an amount sufficient to sensitize said emulsion.

Abstract: A direct positive light-sensitive silver halide photographic material comprising a support having thereon a layer containing a compound represented by the formula (I): ##STR1## wherein R.sub.1 represents an aliphatic residue or an aromatic residue; R.sub.2 represents a hydrogen atom, an aliphatic residue, or an aromatic residue; X.sub.1 and X.sub.2, which may be the same or different, each represents a divalent aromatic residue; and Y represents --R--, --O--R or --S--R-- wherein R represents a divalent aliphatic residue and the O or S is bonded to X.sub.1. The compound is particularly effective in combination with a diffusible dye releasing dye image providing compound having an o-hydroxyarylsulfamoyl group.

Abstract: A direct positive light-sensitive silver halide photographic material comprising a support having thereon a layer containing a compound represented by the formula (I): ##STR1## wherein R.sub.1 represents an aliphatic residue or an aromatic residue; R.sub.2 represents a hydrogen atom, an aliphatic residue, or an aromatic residue; X.sub.1 and X.sub.2, which may be the same or different, each represents a divalent aromatic residue; and Y represents ##STR2## or a direct bond wherein the O or S is bonded to X.sub.1 ; R represents a divalent aliphatic residue and R.sub.3 represents an aliphatic residue or an aromatic residue. The compound is particularly effective in combination with a diffusible dye releasing dye image providing compound having an o-hydroxyarylsulfamoyl group.

Abstract: A method of precipitating silver halide is disclosed in which a methine spectral sensitizing dye is introduced into the reaction vessel in which precipitation of silver halide is performed after nucleation of the silver halide grains has occurred and before completion of silver halide precipitation. The silver halide grains spectrally sensitized in this manner exhibit relatively high minus blue speeds.

Abstract: Light-sensitive silver halide photographic materials to be treated with a hydroquinones-containing developing solution which material comprises a support and at least one hydrophilic colloidal layer coated thereon which contains silver halide grains having an average grain size of 0.05 to 1.5.mu., a tetrazolium compound and a sensitizing dye.

Abstract: Photosensitive silver halide emulsions are prepared by alternating precipitation of silver halide and the addition of a water-soluble iodide salt which replaces a portion of the less soluble halide.

Abstract: A planographic printing plate material comprising a support and a light sensitive layer provided on the support, the light-sensitive layer being composed of (A) an inorganic material; (B) at least one metal and/or metal compound [(A)/(B) are capable of reacting with each other upon application of electromagnetic radiation] and (C) an organic compound capable of affecting the reaction between the inorganic material (A) and the metal and/or metal compound (B), wherein the inorganic material (A), the metal or metal compound (B), and the organic compound (C) are in contact with each other. When the light-sensitive layer is exposed to electromagnetic radiation, a difference in the hydrophilic or oleophilic nature of the exposed areas and the unexposed areas results, whereby a planographic printing plate is obtained which can be mounted on a printing machine and printed without any other treatments.

Abstract: A method of incorporating water insoluble additives (e.g. sensitizing dyes) in colloid layers of photographic silver halide material is provided. The additives are dissolved in a fused water soluble organic compound (e.g. sorbitol or succinimide) and the resulting mixture is either directly added to an aqueous photographic emulsion or is dissolved in the minimum of water or organic solvent and this concentrated aqueous solution is then added to the aqueous photographic emulsion and the whole is then coated as a layer which is part of a photographic material.

Abstract: A method of preparing a spectrally sensitized radiation-sensitive silver halide emulsion is disclosed in which a methine spectral sensitizing dye is added to a reaction vessel prior to the concurrent introduction of aqueous halide and silver salt solutions. The silver halide grains concurrently formed and spectrally sensitized in this manner exhibit relatively high minus blue speeds.

Abstract: An improved direct offset printing plate high in photographic speed which utilizes silver complex diffusion transfer is obtained by using as a silver halide emulsion a direct positive silver halide emulsion which comprises silver halide grains which contain at least 80 mol % of bromide, the surface of said silver halide grains having thereon an electron acceptor and at least one sensitizing dyes selected from the group consisting of those having the following general formula (I): ##STR1## and those having the following general formula (II): ##STR2## (wherein Z, R.sub.1 -R.sub.3, M, A and p and q are as defined in the specification).