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Image Editing II. Simple Blending. = .7 x. + .5 x. Each pixel in a layer is multiplied by the same opacity value. Simple Blending. Opacity values can be visualized as gray levels. 0.7. 0.5. x. x. =. +. Complex Blending. Each pixel in a layer can have a different opacity value - PowerPoint PPT Presentation
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Image Editing II
Simple Blending
= .7 x + .5 x
Each pixel in a layer is multiplied by the same opacity value
Simple Blending
= +
x x
Opacity values can be visualized as gray levels0.7 0.5
• Each pixel in a layer can have a different opacity value
• The opacity values for a layer’s pixels can be visualized as a grayscale image
• This grayscale image is called a “mask”
Complex Blending
Complex Blending
= +
x x
Layer Masks
Selection Mask
• One bit for each pixel1 = selected
0 = not selected
Selection Mask
Image SelectMask0 0 0 0 0 0 0 0 0 00 0 0 0 0 1 1 1 0 00 0 1 1 1 1 1 1 0 00 0 1 1 1 1 1 1 0 00 0 1 0 0 1 1 1 0 00 0 1 0 0 1 1 1 0 00 0 1 1 1 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0
Selecting all yellow and some red pixels
Copy Image SelectMask
0 0 0 0 0 0 0 0 0 00 0 0 0 0 1 1 1 0 00 0 1 1 1 1 1 1 0 00 0 1 1 1 1 1 1 0 00 0 1 0 0 1 1 1 0 00 0 1 0 0 1 1 1 0 00 0 1 1 1 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 00 0 0 0 0 1 1 1 0 00 0 1 1 1 1 1 1 0 00 0 1 1 1 1 1 1 0 00 0 1 0 0 1 1 1 0 00 0 1 0 0 1 1 1 0 00 0 1 1 1 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0
PasteImage PasteMask
Copy Algorithm
for (every pixel [x,y] in the image) { if (selectMask[x,y] == 1) {
pasteImage[x,y] = image[x,y];pasteMask[x,y] = 1;
}else {
pasteMask[x,y] = 0;}
}
Layer Composition Algorithm0 0 0 0 0 0 0 0 0 00 0 0 0 0 1 1 1 0 00 0 1 1 1 1 1 1 0 00 0 1 1 1 1 1 1 0 00 0 1 0 0 1 1 1 0 00 0 1 0 0 1 1 1 0 00 0 1 1 1 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0
Layer = mask+image
Image
for (every pixel [x,y] in the layer) { if (mask[x,y] == 1) { new[x,y] = layer[x,y]; } else { new[x,y] = image[x,y]; }}
New
Moving a Layer
Moving a Layer 0 0 0 0 0 0 0 0 0 00 0 0 0 0 1 1 1 0 00 0 1 1 1 1 1 1 0 00 0 1 1 1 1 1 1 0 00 0 1 0 0 1 1 1 0 00 0 1 0 0 1 1 1 0 00 0 1 1 1 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0
Layer = mask+image
Image
New
0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 1 1 10 0 0 0 1 1 1 1 1 10 0 0 0 1 1 1 1 1 10 0 0 0 1 0 0 1 1 10 0 0 0 1 0 0 1 1 10 0 0 0 1 1 1 0 0 00 0 0 0 0 0 0 0 0 0
Move layer pixels without touching image pixels
Cut
What happens to the deleted pixels?
Replace with background color
Picture Editing
Object representations of pictures
• Types of objects– Lines– Rectangles– Ovals– Text– Curves– Pictures
Text
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)
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
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
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
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 =
Why no missingpixels?
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 =
Does object delete work like images or like text?
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
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
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
Move an object back
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
Changing an imageSequoa -> Sequoia
Select the “a” with magic wand
Changing an imageSequoa -> Sequoia
Drag the “a” to the right
Leaves ugly blank pixels
Change using objects
Sequoa
Select text insertion point
Image object
Text object
Change using objects
SequoiaImage object
Text object
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