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Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Dec 14, 2015

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Page 1: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Raster graphics

Page 2: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Raster graphics

Page 3: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Colour depth

0 1

1 bit pr pixel = 2 combinations (21):

2 bits pr pixel = 4 combinations (22):

00 01 10 11

4 bits pr pixel = 16 combinations(24)8 bits pr pixel = 256 combinations(28)16 bits pr pixel = 65636 combinations(216)24 bits pr pixel =16777216 combinations(224)

Page 4: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Colour depth

1 bpp = 21 = 2 colours

2 bpp = 22 = 4 colours

4 bpp = 24 = 16 colours

8 bpp = 28 = 256 colours

16 bpp = 216 = 65.536 colours

24 bpp = 224= 16.777.216 colours

Page 5: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Colour depth

Page 6: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Filfe formats

• TIF (Tagged Image File Format) 1-32 bit

• BMP (Windows Bitmap) 8-24 bit

• TGA (Targa) 24-32 bit

• JPG (JPEG – Joint Photographics Expert Group) 8-24 bit

• GIF (Graphics Interchange Format) 1-8 bit

• PNG (Portable Network Graphics) 4-24 bit

F.ex:

Page 7: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Gif-format

• Max 256 colours

• Good for logos, line drawings, buttons

• May be transparent

• May be animated

• Use LZW compression

Page 8: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Gif-format palette

System paletteGoes on 256-colours screens. ‘Uses ‘dithering’

Optimized paletteScreen set to more than 256 colours

Page 9: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Jpg-formatet

• 24 bits colour depth, ie 16.7 million colours(or 8-bit grey scale)

• Good for photos

• Extreme compression possible

Page 10: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Jpg compression

766 x 782 pixels, 24 bitTIF no compression1720 KB

766 x 782 pixels, 24 bitJPG compression 25104 KB

Page 11: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Jpg compression

• Compression factor 1-99

250x200 pixels, 24 bitKompression 15

250x200 pixels, 24 bitKompression 99

11,5 kb 1,7 kb

Page 12: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Jpg / gif …photos

jpg, 11,5 kb gif, 22,4 kb

200x250 pixels 200x250 pixels

Page 13: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Jpg / gif …drawing

gif, 6,08 kb

jpg, 5,5 kb

Page 14: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Anti aliasing

Page 15: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Digitalization

Analog(photo)

Digitalization

(f.x. Scanning)

Digital(Raster image)

Page 16: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Digitalization

Flatbed scanner

Lamp

Photo cells

Image

Direction of scan

Scanner head

Data for computer

Page 17: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Digitalization

Digital camera

CCD chipLens

light

Data forMemory

Page 18: Raster graphics. Colour depth 01 1 bit pr pixel = 2 combinations (2 1 ): 2 bits pr pixel = 4 combinations (2 2 ): 00011011 4 bits pr pixel = 16 combinations(2.

Scanning - DPI

• DPI = Dots Per Inch –

• Computer screen = 72 DPI – 10x10 cm output = 288 x 288 pixels (72 / 2,5 x 10)

• Standard laser print = 600 DPI– 10x10 cm output = 2400 x 2400 pixels (600 / 2,5 x 10)