November '20

Issue link:

Contents of this Issue


Page 61 of 118

G R A P H I C S - P R O. C O M 2 0 2 0 N O V E M B E R G R A P H I C S P R O 5 7 and brightness (how dark or light it is), also in percentages. CMYK interprets the colors into percentages of the four basic printer's inks: cyan, magenta, yellow, and black. LAB is a device-independent color mod- el based on the human eye. It expresses color as three values: L for the lightness from black (0) to white (100), A from green (−) to red (+), and B from blue (−) to yellow (+). LAB was designed so that the same amount of numerical change in these values corresponds to roughly the same amount of visually perceived change. The LAB color space is typically used when graphics for print have to be converted from RGB to CMYK. EYEDROPPERS The value of individual pixels or groups of pixels can be measured. Accurate color correction would be impossible without knowing the color values of specific areas of pixels. Pixels are measured with the Eyedropper or Color Sampler tool and the Info panel. The Eyedroppers can be configured in the Options bar to measure a point sample, or the average value of a group of pixels. For higher resolution or large-format images, a five by five value or greater is recommended. The Info panel, found in the Window menu, displays the specific information that the Eyedroppers detect. When the Eyedroppers are dragged over an image, the numbers rapidly change as the tools touch pixels with different values. When a pixel is sampled by the Color Sampler tool, a numbered target is deposited on the image and the data appears in a separate field. When a color or tonal adjustment is applied, two sets of numbers are displayed (Figure 7). The number on the right is the initial sample. The number on the left conveniently changes as the adjustment is made and can be compared to the values of the original sample point. HISTOGRAMS While the Eyedroppers and Info panel are essential for measuring the colors of indi- Sometimes the on-screen image doesn't ac- curately represent the image's actual colors, so it's advisable to calibrate your monitor and color manage your image before mak- ing color adjustments. vidual pixels, the histogram is the primary measurement device for determining global color trends. When you first open an im- age, scrutinize it carefully to determine what the colors on your monitor represent. 720-746-9075 | Free Shipping On Supply Orders Over $ 99 Screen printing supplies, Siser HTV supplies, and Equipment.

Articles in this issue

Links on this page

view archives of GRAPHICS PRO - November '20