Abstract: A purification method of dihydroxybenzene comprising the following steps, for obtaining purified dihydroxybenzene from crude dihydroxybenzene containing at least isopropenylphenol and hydroxyacetophenone as impurities: first extraction step, distillation step, second extraction step, and recovery step.

Abstract: A purification method of dihydroxybenzene comprising the following steps, for obtaining purified dihydroxybenzene from crude dihydroxybenzene containing at least isopropenylphenol and hydroxyacetophenone as impurities: first extraction step: water is added to crude dihydroxybenzene to prepare a dihydroxybenzene aqueous solution A, then, the solution is subjected to extraction by allowing it to contact with an extraction solvent (1), to be separated into a first fraction containing dihydroxybenzene, hydroxyacetophenone and water and a second fraction containing isopropenylphenol and the extraction solvent (1), distillation step: the first fraction obtained in the first extraction step is subjected to distillation, to be separated into a third fraction containing water and a fourth fraction containing dihydroxybenzene and hydroxyacetophenone, then, the fourth fraction is subjected to distillation, to be separated into a fifth fraction as purified dihydroxybenzene and a sixth fraction as dihydroxybenzene contain

Abstract: An image recognition apparatus for recognizing a specific image in an object image using image signals of the object image, the specific image having a possibility of being rotated. The image recognition apparatus includes an image information extraction unit for extracting an object image from the image signals as a candidate for recognition of the specific image and for extracting feature values from the object image using the image signals, and a match determining device coupled to the image information extraction unit for recognizing the specific image in the object image by a comparison of the extracted feature values from the object image with reference data for the specific image. The match determining device is controlled using the reference data according to an easy to determine rotation characteristic and difficult to determine rotation characteristic in the reference data for the specific image.