Diffusion transfer method

This is one of the instant photography methods, and is also abbreviated to DTR from its English name. After the photo is taken, the development process takes place in the photosensitive material, so the photo can be viewed immediately. A silver halide emulsion layer coated on a transparent support is first brought into contact with an image-receiving layer coated on another support, and after exposure, a viscous developer is spread between the two for development. Color photosensitive materials that use negative emulsions (exposed areas are developed) use dyes that do not diffuse due to oxidation. This allows the image-forming dye to diffuse and be transferred to the image-receiving layer in the unexposed areas where the silver halide particles are not developed, forming a positive image. When an autopositive emulsion (unexposed areas are developed) is used, the dye is released by reacting with the oxidized form of the developing agent, causing the dye to diffuse in the unexposed areas, forming a positive image in the image-receiving layer. In black-and-white photosensitive materials, the silver halide particles that were not exposed and developed are dissolved by a silver halide dissolving agent in the developer and transferred to the image-receiving layer. A positive image is obtained by physically developing this.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

インスタント写真法の一つで，英語名からDTRとも略称される．撮影後の感光材料中で現像処理が行われ，すぐに写真を見ることができる．透明支持体に塗布したハロゲン化銀乳剤層と，ほかの支持体に塗布した受像層とをあらかじめ密着させておき，露光後，粘ちゅうな現像液を両者の間に展開させて現像する．ネガ型の乳剤(露光部が現像される)を用いるカラー感材では，酸化によって拡散しなくなる色素を用いる．これにより，ハロゲン化銀粒子が現像されない未露光部で画像形成色素が受像層に拡散して転写され，ポジ像が形成される．オートポジ型乳剤(未露光部が現像される)が用いられる場合には，現像主薬の酸化体との反応で色素を放出させることにより，未露光部で色素が拡散し，受像層にポジ像が形成される．黒白感材では，未露光で現像されなかったハロゲン化銀粒子を現像液中のハロゲン化銀溶解剤で溶かし，受像層に転写させる．これを物理現像することによってポジ像を得る．

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