Image Editing II

Simple Blending =.7 x+.5 x Each pixel in a layer is multiplied by the same opacity value

Simple Blending =+ xx Opacity values can be visualized as gray levels

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

=+ xx Layer Masks

Selection Mask One bit for each pixel 1 = selected 0 = not selected

Selection Mask ImageSelectMask Selecting all yellow and some red pixels

Copy ImageSelectMask PasteImagePasteMask

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 Algorithm 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

Layer = mask+image Image New 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 missing pixels?

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

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 image Sequoa -> Sequoia Select the “a” with magic wand

Changing an image Sequoa -> 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 Sequoia Image 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