CSE, UTA 1

Visible Spectrum

CSE, UTA 2

Visible Spectrum

380 nm 780 nm

CSE, UTA 3

BLACKBODY RADIATION

CSE, UTA 4

Human Spectral Sensitivity

CSE, UTA 5

Rod and Cone density

CSE, UTA 6

Cone Details

Current understanding is that the 6 to 7 million cones can be divided into "red" cones (64%), "green" cones (32%), and "blue" cones (2%) based on measured response curves. They provide the eye's color sensitivity. The green and red cones are concentrated in the fovea centralis . The "blue" cones have the highest sensitivity and are mostly found outside the fovea, leading to some distinctions in the eye's blue perception.

The cones are less sensitive to light than the rods, as shown a typical day-night comparison. The daylight vision (cone vision) adapts much more rapidly to changing light levels, adjusting to a change like coming indoors out of sunlight in a few seconds. Like all neurons, the cones fire to produce an electrical impulse on the nerve fiber and then must reset to fire again. The light adaption is thought to occur by adjusting this reset time.

The cones are responsible for all high resolution vision. The eye moves continually to keep the light from the object of interest falling on the fovea centralis where the bulk of the cones reside.

CSE, UTA 7

The CIE standard observer color-matching functions

Tristimulus values

Other observers, such as for the CIERGB space or other RGB color spaces, are defined by other sets of three color-matching functions, and lead to tristimulus values in those other spaces

CSE, UTA 8

The CIE xy chromaticity diagram The CIE XYZ color space was deliberately designed so that the Y parameter was

a measure of the brightness or luminance of a color. The chromaticity of a color was then specified by the two derived parameters x and y, two of the three normalized values which are functions of all three tristimulus values X, Y, and Z:

CSE, UTA 9

CHROMATICITY DIAGRAM

CSE, UTA 10

RGB Space

CSE, UTA 11

RGB Space

CSE, UTA 12

Hue Intensity Color Circle

CSE, UTA 13

Additive and Subtractive

CSE, UTA 1414

Color Space – YCbCr

YCbCr Used for: digital video encoding, digital

camera Y: luminacance Cb: blue chroma Cr: red chroma

CSE, UTA 1515

Color Space – YCbCr

Conversion from RGB: Y=0.299(R-G) + G + 0.114(B-G) Cb=0.564(B-Y) Cr=0.713(R-Y) The Matrix form:

0.299 0.587 0.114

0.168636 0.232932 0.064296

0.499813 0.418531 0.081282

Y R

Cb G

Cr B

CSE, UTA 16

RGB to YIQ & CMY Conversion

0.299 0.587 0.114

0.595716 0.274453 0.321263

0.211456 0.522591 0.311135

Y R

I G

Q B

CSE, UTA 1717

Color Space – YUV

YUV Used for: video encoding for some

standard such as NTSC, PAL, SECAM Axes: Y: luma U: blue chroma V: red chroma

CSE, UTA 1818

Color Space – CMYK

Used for printers (subtractive color mixing) Cyan Magenta Yellow K: black

C = 1 - RM= 1 - GY = 1 - B

K = min (C, M, Y)

CSE, UTA 1919

Color Space – YUV

Conversion from RGB: Y=0.299R+0.587G+0.114B U=0.436(B-Y)/(1-0.114) V=0.615(R-Y)/(1-0.299) The Matrix form:

0.299 0.587 0.114

0.14713 0.28886 0.436

0.615 0.51499 0.10001

Y R

U G

V B

CSE, UTA 20

Screen

pixel (0,0)

x

y

pixel (n,0)

CSE, UTA 21

Frame Buffer

pixel (0,0)pixel (1,0)

pixel (n,m)

CSE, UTA 22

Bit Planes

4 -bits/pixel

CSE, UTA 23

Color Look-up Table

R

G

B

Screen

FrameBuffer Color Tables

CSE, UTA 24

Direct Color Visual

R

G

B

Screen

FrameBuffers Color Tables

CSE, UTA 25

Image formats TIFF

Platforms: Mac/DOS/Unix Owner: Aldus/Microsoft Notes: TIFF (Tag ImageFile Format) is an international standard for storing and

interchanging bitmaps between applications and hardware platforms. It is almost always supported by major applications that provide bitmap manipulation. The format consists of items called tags which are defined by the standard. Each tag is followed by a tag dependent data structure. Supports most color spaces and compression methods.

PCX Platforms: DOS Owner: ZSoft Corp Notes: The oldest and most commonly supported format on DOS machines. Can support

indexed or full 24 bit color. Run length encoding only. GIF

Platforms: Mac/DOS/Unix Owner: CompuServe Notes: GIF is a rather underfeatured but quite popular format. It is used the most on

bulletin boards and on the worldwide internet. It is limited to 8 bit indexed color and uses LZW compression. Can include multiple images and text overlays.

CSE, UTA 26

Image formats PICT

Platforms: Mac Owner: Apple Notes: PICT is a Macintosh only format, indeed it is virtually impossible for it to exist on

any machine but the Macintosh. The interpretation of a PICT is handled by the Macintosh operating system and thus is supported by almost all Macintosh applications. This format is responsible for the successful transfer of image data on the Macintosh and is used in cut/copy/paste operations. Supports most color spaces and compression methods including JPEG.

Format: GEM Platforms: DOS/Atari Owner: Digital Research Notes: Supported by GEM operating system.

Format: IFF/ILBM Platforms: Amiga Owner: Electronic Arts Notes: Supports four bit color map and 24 bit direct color..

CSE, UTA 27

Image formats Format: TARGA

Platforms: Mac/DOS Owner: TrueVision Inc Notes: Originally designed for VISTA data capture boards. Little more than a RAW format

with some extra header information. Format: BMP/DIB

Platforms: DOS/Windows Owner: Microsoft Notes: Microsoft Windows format, rarely supported elsewhere. Supports 1,2,4,8, and 32

bit color images Format: Sun raster

Platforms: Sun Owner: Sum MicroSystems Notes: Only supported by Sun. Use RLE and either 8 bit grayscale or 24/32 bit color.

CSE, UTA 28

Image formats Format: XBM

Platforms: X systems Owner: MIT X Corp Notes: Specifically for X windows system bitmap routines, used for cursors and icons.

Format: XWD Platforms: X systems Owner: MIT X Corp Notes: Screen save format under X windows. Implements black and white through to 24

bit direct color.