ORIGINALS & FILMS IMAGING TECHNOLOGY

ORIGINALS 2  The originals can be classified into three major groups:  Line originals  Tone originals  Color originals

ORIGINALS 3  Line originals:  Picture in solid black images on a white background eg. Pen and ink drawings  Tone originals:  Pictures in black and white, but with intermediate areas of varying density eg. Photographic prints, chalk drawings, pencil sketches and wash drawings  Color originals:  Pictures presenting in line and tone in color eg. Color transparencies

LINE ORIGINALS 4 Line originals must be presented in only in two pieces: dense, opaque black and clean, reflective white The requirements: 1. All image areas must be completely black and firmly drawn with sharp edges 2. The background must be smooth white surface of high reflectance 3. Background materials need to be opaque and reasonably stiff or dry-mounted

LINE ORIGINALS 5 Black and white line art images (graphics, etc.) require little effort. The image represents binary data since only black or white elements are present.

TONE ORIGINALS Embraces all pictures created in neutral tones or grays of varying strength ranging from white to solid black 6

COLOR ORIGINALS To reproduce the colored picture the printer must transfer layers of ink onto the white paper which will control exactly the same amount of colored light as the original did 7

HALFTONE PROCESS 8 In printing, a technique of breaking up an image into a series of dots so as to reproduce the full tone range of a photograph or tone art work. The eye has limited resolving power and, at a distance, is tricked into seeing these dots as continuous tone.

HALFTONE PROCESS 9 Breaking up is usually done by a screen inserted over the plate being exposed. The screens are made with a varying number of lines per inch, depending on the application; for newspapers, the range is 50 to 85, and for magazines, 100 to 120. The highest quality reproduction requires 120 to 150 lines per inch.

FILMS 10

FILMS 11 Panchromatic Film Orthochromatic Film Infra Red Film

ORTHOCHROMATIC FILM 12 Orthochromatic film is sensitive to the blue end of the spectrum, reaching the wavelength which produces green light, but not red. Orthochromatic film makes warm colours appear black and cool colours appear pale.

PANCHROMATIC FILM 13 Panchromatic film is a type of black&white photographic film that is sensitive to all wavelengths of visible light.black&whitephotographic filmwavelengthsvisible light A panchromatic film produces a realistic reproduction of a scene as it appears to the human eye. Almost all modern films used are panchromatic As naturally prepared, silver halide emulsions are much more sensitive to blue and UV light than to green and red wavelengths.silver halideemulsions

INFRA RED FILM 14 Infra red film is used in both scientific and creative photography. It is a panchromatic film which has sensitivity skewed to the red end of the spectrum

REQUIREMENTS ON FILMS 15 The types of film used particularly for film image setters are subject to the following requirements:  they must be dimensionally stable,  the exposed/dark areas must have good opacity (optical density D=4),  the unexposed/light areas must be crystal clear (optical density D=0.05),  they must have very short exposure times, since the dots are imaged consecutively and the total imaging time must remain acceptable,  they must have sharp edge definition,  they must have high resolution

SENSITOMETRY 16 The scientific study of a photosensitive material to different levels of exposures. How is it done? Producing a sensitometric strip and plotting a characteristic curve. A film containing number of areas with different optical densities from white (fully transparent) to black (fully opaque)

Why is the study important? 17 To produce images with optimum contrast that reveal high details of the object examined. Optimum contrast? Low contrast (long scale contrast) High contrast (Short scale contrast)

Optimum contrast PHOTOGRAPHIC IMAGES High contrast Low contrast

DENSITOMETRY 19 Densitometry is the quantitative measurement of optical density in light-sensitive materials after exposure to light.measurementoptical density The corresponding measuring device is called a densitometer densitometer

TRANSMISSION DENSITOMETER 20 Transmission densitometers measure transparent materials The densitometer is basically a light source aimed at a photoelectric cell.photoelectric cell It determines the density of a sample placed between the light source & the photoelectric cell from differences in the readings.photoelectric cell

NOW ITS YOUR TURN TO ANSWER… 21 Types of originals? line, tone, color Half tone screen angles for process colors? C 15deg, M 75deg, Y 90deg, K 45deg Types of films? orthochromatic, panchromatic, infrared Sensitometry? The scientific study of a photosensitive material to different levels of exposures. Densitometer? measuring device used to measure optical density in light sensitive materials

ASHOK K S THANK YOU!!!