Abstract: A method and apparatus for reproducing a desired portion of letters and/or patterns in an original on a copying paper, wherein the system is computerized so as to obtain the necessary information from the data stored with respect to the distance components derived from the original, and on the basis of the information, an area excluding the desired portion of the original is deelectrified so as to exclude the area from the expected reproduction of the desired portion on the copying paper.

Abstract: Controlling the exposure time in the reciprocity law failure range of a photosensitive material, in a picture reproducing machine, wherein the response time variation cause by variations is corrected according to the operational equation for the reciprocity law when the photosensitive material is in its linear range, by exposing said photosensitive material for a time t.sub.m in accordance with the relationship; ##EQU1## wherein T.sub.0 is the correct exposure time in the absence of reciprocity law failure, M.sub.i is the desired reproduction scale and P is an empirically determined coefficient which is greater for enlargements than reductions.

Abstract: A method and machine for automatic focusing in a projection system with continuously variable magnification, wherein an original picture is projected onto a photosensitive material by a focusing lens, wherein one of these three members is fixed and the other two members are moved in a direction of a light axis by moving means, wherein the positions of the two moving members are detected by detectors, and wherein control means controls that, when the magnification of a picture image is changed, one moving member having a larger moving rate than that of the other moving member is moved ahead of the other moving member and the other moving member is moved dependent on the one moving member so that the picture image projected may constantly be focused onto the photosensitive material.

Abstract: A method and apparatus for correcting the reciprocity law failure of a photosensitive material to be exposed, for use in a picture reproducing machine such as a process camera are disclosed. Luminous energies of an original picture and a standard picture are detected by a light detector, and then the exposure luminous energy is compared with the standard luminous energy by an arithmetic unit. Then, an exposure time is calculated in a calculator by using the comparison result and fundamental data such as the standard luminous energy, a standard exposure time predetermined, and a correction factor predetermined, which are recorded in data setup means.

Abstract: A color correction apparatus for a duplicate camera wherein three color correction filters of three primary colors are provided and are selectively interposed into the exposure light path, is disclosed. An arithmetic unit is connected to a color correction value setup means which sets up color correction values of colors to be removed from an original picture, and it receives these density values as negative values and subtracts the minimum value thereof from each of the other density values to outputs a color correction signal. Then, a control unit connected to the arithmetic unit controls the color correction filters so that they may be interposed into the exposure light path according to the color correction signal.