1 / 16

Color Standards

Color Standards. A pixel color is represented as a point in 3-D space. Axis may be labeled as independent colors such as R, G, B or may use other independent indicators such as Hue, lightness, saturation. RBG, HSV, HSL are the most popular. RGB. RGB (Red green blue)

alair
Download Presentation

Color Standards

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Color Standards • A pixel color is represented as a point in 3-D space. Axis may be labeled as independent colors such as R, G, B or may use other independent indicators such as Hue, lightness, saturation. • RBG, HSV, HSL are the most popular. 240-373 Image Processing

  2. RGB • RGB (Red green blue) • For CRT display (TV, computer monitor) • Additive combination of r g and b 240-373 Image Processing

  3. HSV • HSV (Hue Saturation Value) Hue is effectively a measure of the wavelength of the main color. It has a value between 0-255 (0-360o, Red = 0o, Green=120o and Blue=240o.) Hue can be calculated from RGB values as follows: Rh = R - min (R, G, B) Gh = G - min (R, G, B) Bh = B - min (R, G, B) At least on of these values is 0. Hue value is in between. 240-373 Image Processing

  4. HSV For example if Rh = 0 Hue angle = (240xBh + 120xGh ) / (Bh + Gh) If two are zero, then hue is the angle corresponding to the third non-zero color. If three are zero, then there is no color hue. The monitor will display a gray level (between black and white). 240-373 Image Processing

  5. Saturation • Saturation is the amount of pure hue in the final color If Saturation = 0, final color is without hue ( white light only) If Saturation = 255, no white light in final color Saturation = (max(R,G,B) - min (R,G,B)) / max(R,G,B) 240-373 Image Processing

  6. Value • Value (brightness) is a measure of the intensity of the brightest component and given by Value = max(R,G,B) 240-373 Image Processing

  7. The HSV Model 240-373 Image Processing

  8. HSV Example Given R=100, G=200, B= 40, convert this RGB color model to HSV. Rh = 100 - min(100,200,40) = 60 Gh = 200 - min (100,200,40) = 160 Bh = 40 - min (100,200,40) = 0 H = (60*0 + 160*(120*256/360))/(60+160) 240-373 Image Processing

  9. HSV Example (Continued) Saturation = (max(R,G,B) - min (R,G,B)) / max(R,G,B) = (max(100,200,40)-min(100,200,40))/ max(100,200,40) = (200-40)/200 = 0.8 = 80% Saturation = 80*256/100 = 204 Value = max(100,200,40) = 200 = 200*100/256 = 78% 240-373 Image Processing

  10. 240-373 Image Processing

  11. HLS HLS (Hue Lightness Saturation) • Similar to HSV except that the hue angle start at Blue = 0o, and the model is double cone with a lightness axis going from L=0 (black) to L=1 (white) • For HLS, hue is calculated the same way as for HSV model except Blue = 0 and lightness and saturation are given by: • Lightness = (max(R,G,B) - min(R,G,B))/2 (max+min)/(max-min) if L <= 0.5 • Saturation = (max-min)/(2-max-min) otherwise 240-373 Image Processing

  12. HLS 240-373 Image Processing

  13. CMY & CMYK • CMY (Cyan Magenta Yellow) เป็นระบบสีที่พัฒนาขึ้นมาใช้สำหรับการพิมพ์ภาพสีโดยมีสีหลักคือสี Cyan Magenta และ Yellow ซึ่งเรียกว่า Subtractive primaries Color (สีแดง เขียวและน้ำเงิน เรียกว่า Additive primaries Color) ระบบสีแบบ CMY สามารถหาได้โดยการนำเอาสีในระบบ RGB ลบกับสีขาวดังนี้คือ 240-373 Image Processing

  14. CMY & CMYK • ระบบสี CMY จะนำไปใช้สำหรับการพิมพ์ภาพสีแต่ยังไม่ดีเท่าที่ควรเนื่องจากไม่ยังไม่สามารถสร้างสีดำได้อย่างถูกต้อง ดังนั้นจึงมีการใช้ระบบ CMYK แทนโดย K แทนสีดำ 240-373 Image Processing

  15. The Human Vision • Better than any camera yet developed • Eye has 2 classes of discrete light receptors; Cones and rods • 6-7 million cones, sensitive to bright light • >= 75 Million rods, sensitive to light intensity but not color • eye color perceptions 240-373 Image Processing

  16. Color Additive • Problem with CRT 240-373 Image Processing

More Related