| 摘要 |
PURPOSE: To reproduce a halftone original picture by compressing or expanding by using a continuous tone correcting mask with the halftone original picture to apply for projection exposure so as to improve the reproduction of the tone. CONSTITUTION: The halogenated emulsion layer of a mask film 5 under exposure is made to approach a halftone image to expose through the halftone image to form a potential mask image being a descreened image, namely a continuous tone image in the mask film 5. Exposure for manufacturing this mask image (in order to improve the reproduction of the tone) is decided by a linear relationship between the number of screen lines in the original picture and optical density selected so that the mask may be provided with 0 to 10% dot value with respect to the area of the original picture. Namely the improved reproduction of the tone is obtained by using the mask image for projection exposure and maximum density (density in the area of 3% dot value in the halftone original picture used for projection exposure) is proportional linearly and directly with the number of the screen lines and the shape of line in the halftone original picture used for projection exposure. |
