Class 39 — April 22

Doing the mash

It’s simply smashing — To have people on the Lawn — If they watch their steps

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Always look both ways

• Back and ahead

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Agenda

• Combining photos for homework 29

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Module mash.py

• Supports the creation of a new image that is a mash up of two existing images — bg and fg. The new image has bg as its background. The pixels in fg that are dissimilar to the back screen color are copied on top of the background.

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Downloads

• Module mash.py

• Tester smashing.py

• Used by module mash for some simple holistic testing of its capabilities.

• Tester me_smash.py

• Mashes a class selfie with the dinosaur

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Primary function (already written)

• combine( bg, fg, sx, sy, back_screen )

• Returns mash up of background image bg and foreground image fg, where the pixels in fg that are dissimilar to back_screen are copied on top of the background.

• The mash up uses location (sx, sy) as the spot in the background to start the lay over of fg.

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Convenience functions to be written

• similar( p1, p2, max_allowable=THRESHOLD )

• Returns whether the distance between pixels p1 and p2 is less than the max allowable threshold.

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• is_background( p, back_screen )

• Returns whether p is similar to the back_screen color.

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• inbounds( spot, img )

• Returns whether spot lies on img; that is whether the x-value and y-value for spot are nonnegative, the x-value is less than img width, and the y-value is less than img height.

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• colorable( spot, img, p, back_screen )

• Returns whether both spot is a location on img and color p is not similar to color back_screen.

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Already written convenience functions

• distance( p1, p2 )

• Returns the RGB difference between colors p1 and p2.

• clean_up( original, back_screen )

• Returns a new copy of the original, where those pixels in original similar to color back_screen are replaced by back_screen.

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