Monday, 3 September 2012

Some Key Elements of Digital Printing

Some Key Elements of Digital Printing - RESOLUTION – At each stage of digital imaging the term “resolution” has a different usages resolution has a different usages. Resolution is concerned with the amount of digital information present. It is now common practices to refer to resolution in term of pixels are known as raster image has four important properties: size, value, color depth and location.

–The optimum resolution for a digital device is its optical resolution with scanners, the optical resolution with scanners, and the optical resolution refers to the number of times per unit length the original is sampled. Interpolation involves using mathematical algorithms to inserts new pixels between existing ones. Each new pixel is given a value of the surroundings pixel. Hence, interpolation does not add new detail; in fact the quality of the interpolated image will be reduced. The grater the interpolation the more the image quality suffers. However, this knowledge can be used to produce unusual results .

COLOR DEPTH AND DYNAMIC RANGE- Color or bit depth express the maximum number of colors or  gray levels an image capture device can produce for each pixel when bit depth is specified for a device ,for example 24 bit, it really means that it can re produce 2/24 different colors . since most color devices work in RGB mode , each of the three RGB channels of a 24 bit, devices is assigned 8 bit of information, producing a total of 2/8(256) shades per channel.

COLOR SPACES – Color is all around us it is something most people take for granted. Ask some are what color grass is and they will usually reply, “Green”. But like all colors there are many different greens ask the some person to describe the exact green in detail and you are confronted with a problem: color is a perceptual function of the human brain and doesn’t lend itself to linguistic description. Color spaces or color models, are scientifically formulated methods of quantifying color Different color spaces are used for different purpose. Artist use the system known as HLS (lightness, saturation)or HSB (hue, lightness, saturation,)or use RGB (red ,green, blue), CMYK(cyan, magenta, yellow ,black, -the “key”  color space.

SCANNING RESOLUTION- Before scanning either a print or afilm original you should decide what the final digital image is to be used for. This will allow you to calculate the optimum scanning resolution and magnification so that the digital file contains the optimum amount of information. Too much information in an image wasted while too little will not produce the desired quality. Fortunately, most scanning software allows you to specify the image size you want and the output resolution desired. The software then calculates the required input resolution at which the original needs be scanned .This save you doing the mathematics.

MONOCHROME NEGATIVE – This image of a sty tablet was scanned as a black-and-white negative. The relevant densities for each step are also shown.

COLOR NEGATIVE – The same step tablet was scanned this time as a color negative. The density range is almost identical to the black-and-white negative scene: The image was converted to grayscale to make comparison easier.

MONOCHROME TRANSPARANCY- Scanning the step tablet as a black-and-white transparency has produced a totally different tone scale. All the steps are visible, indicating that the density range indicating that the density range is increased when scanning transparencies. This can be useful for a negative with too much contrast. Scan it as a transparency then invert the image.

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