Image Editing II

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Image Editing II
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Simple Blending
.7 x
.5 x
Each pixel in a layer is multiplied by the same
opacity value
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Simple Blending
Opacity values can be visualized as gray levels
0.7
0.5
x
x


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Complex Blending

• Each pixel in a layer can have a different
  opacity value
• The opacity values for a layers pixels can be
  visualized as a grayscale image
• This grayscale image is called a mask

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Complex Blending
Layer Masks
x
x


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Selection Mask

• One bit for each pixel
• 1 selected
• 0 not selected

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Selection Mask 
Image
SelectMask
Selecting all yellow and some red pixels
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Copy 
Image
SelectMask
PasteImage
PasteMask
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Copy Algorithm

• for (every pixel x,y in the image)
• if (selectMaskx,y 1)
• pasteImagex,y imagex,y
• pasteMaskx,y 1
• else
• pasteMaskx,y 0

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Layer Composition Algorithm
Image
Layer maskimage 
for (every pixel x,y in the layer) if
(maskx,y 1) newx,y layerx,y
else newx,y imagex,y
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Moving a Layer
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Moving a Layer 
Image
Layer maskimage 
Move layer pixels without touching image pixels
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Cut
What happens to the deleted pixels?
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Picture Editing
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Object representations of pictures

• Types of objects
• Lines
• Rectangles
• Ovals
• Text
• Curves
• Pictures

Text
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Picture array of drawing objects

• 0) Rect(10,10,50,40,tan,yellow)
• 1) Oval(0,30,40,20,blue,purple)
• 2) Line(20,0,20,80,gray)

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Adding an object

• 0) Rect(10,10,50,40,tan,yellow)
• 1) Oval(0,30,40,20,blue,purple)
• 2) Line(20,0,20,80,gray)
• 3) Text(25,25,Hello,
• black,Times )

Hello
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Selecting an object

• 0) Rect(10,10,50,40,tan,yellow)
• 1) Oval(0,30,40,20,blue,purple)
• 2) Line(20,0,20,80,gray)
• 3) Text(25,25,Hello,
• black,Times )

Hello
CurObj 2
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Deleting an object

• 0) Rect(10,10,50,40,tan,yellow)
• 1) Oval(0,30,40,20,blue,purple)
• 2) Line(20,0,20,80,gray)
• 3) Text(25,25,Hello,
• black,Times )

Hello
CurObj 2
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Deleting an object

• 0) Rect(10,10,50,40,tan,yellow)
• 1) Oval(0,30,40,20,blue,purple)
• 2) Text(25,25,Hello,
• black,Times )

Hello
CurObj
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Deleting an object

• 0) Rect(10,10,50,40,tan,yellow)
• 1) Oval(0,30,40,20,blue,purple)
• 2) Text(25,25,Hello,
• black,Times )

Hello
Does object delete work like images or like text?
CurObj
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Moving an object

• 0) Rect(10,10,50,40,tan,yellow)
• 1) Oval(0,30,40,20,blue,purple)
• 2) Text(25,25,Hello,
• black,Times )

Hello
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Moving an object

• 0) Rect(10,10,50,40,tan,yellow)
• 1) Oval(30,30,40,20,blue,purple)
• 2) Text(25,25,Hello,
• black,Times )

Hello
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Changing an object

• 0) Rect(10,10,50,40,tan,yellow)
• 1) Oval(30,30,40,20,blue,purple)
• 2) Text(25,25,Hello,
• red,Arial )

Hello
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Move an object back
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Move an object back

• 0) Oval(30,30,40,20,blue,purple)
• 1) Rect(10,10,50,40,tan,yellow)
• 2) Text(25,25,Hello,
• red,Arial )

Hello
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Changing an imageSequoa -gt Sequoia
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Changing an imageSequoa -gt Sequoia
Leaves ugly blank pixels
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Change using objects
Text object
Image object
Sequoa
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Change using objects
Text object
Image object
Sequoia
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Compare

• Why are images better than objects?
• More realistic pictures
• Easy to generate with cameras and scanners
• Why are objects better than images?
• Less space
• Easier to make changes