Currently,most printing unit allocates desktop publishing system.But a lot of units especially little company lack of image making staff.Additionally, with low technology level and being other objective factor,the printing's making and quality of many color picture are not to be satisfied,which falls behind with international publication for long distance.We can often hear a lot of art editor and　 cameraman to complain that the printing quality of current pictorial,album of painting and periodical magazine is not good.The manuscript can't be restore.Color is distort seriously and some color becomes color pattern batch which level is confused.Even the color of original manuscript's person and scenery is serious color cast.All above are mostly caused by improper color separation scanning.There are several main factor for that.First,they adopt the commen platform scanner with inferior quality of color separation.Second,the operator lack operation method of separation scanning concept and standardization,who depend on the screen completely,as neglect powerful function and the advanced technique of the high grade professional scanner and electrical color separation machin network.Third,the operating people lack aesthetic level and they have no correct analysis ability to set correct parameter and apt adjustment according to the characteristic of various original manuscripts. Is natural, there are very few customer not know the business and command groundlessly.
　 Practice prove that the key of color picture's quality is separation scanning technology.Because simulated color photograph and reversal print film must be converted to digital image by scanning for transmitting in the flow of digitalised technology in prepress system.In this flow,on one hand,we should know how to apply the scan to get the best color level information from original manuscript.On　 the other hand,the format of image from scanning usually is RGB which should be converted to CMYK,as　 is the key of the color separation.It need consider some parameter such as printability of oil and paper,dot enlargement extent,gray balance parameter,level of black plate,GCR or UCR separation　 mode.We should set these parameter well so as to output the high quality separation film.Also, separation scanning has technical and artistry.We should set the optimum parameter such as gray balance,level contrast,color correcting, definition etc based on technical aspect.Meanwhile we should deal with the relation well such as keynote, saturation,distance of space,lightness and darkness,
　 Variousness of optical image etc based on aesthetics aspect.The two aspects of operator's level is great important to the quality of the printing product.Therefore, if we want to raise the quality of color printing product,we must make up our mind to grasp the separation scanning technology and raise the inner quality of operator.