Programming Reference:BitmapImage Class - Revision history

Mellinger: /* Addition and Subtraction */

2008-12-20T14:56:53Z

Addition and Subtraction

← Older revision		Revision as of 14:56, 20 December 2008
Line 32:		Line 32:

	==Addition and Subtraction==		==Addition and Subtraction==
	~~Difference~~ images, and restoring original images from a reference frame followed with difference frames, is possible using addition and subtraction:		Computing difference images, and restoring original images from a reference frame followed with difference frames, is possible using addition and subtraction:
	BitmapImage image1, image2;		BitmapImage image1, image2;
	BitmapImage diff = image1 - image2;		BitmapImage diff = image1 - image2;

Mellinger: /* WriteBinary(ostream), ReadBinary(istream) */

2008-12-20T14:55:35Z

WriteBinary(ostream), ReadBinary(istream)

← Older revision		Revision as of 14:55, 20 December 2008
Line 17:		Line 17:
	This function replaces an image's "background" with pixels from the image specified as argument. "Background" pixels are pixels with the most significant bit set to 1.		This function replaces an image's "background" with pixels from the image specified as argument. "Background" pixels are pixels with the most significant bit set to 1.
	===WriteBinary(ostream), ReadBinary(istream)===		===WriteBinary(ostream), ReadBinary(istream)===
	Writes/reads the image's data to or from the specified streams. An image's stream representation is always run-length encoded, which is especially efficient in conjunction with temporal compression, i.e. sending sequences of ~~image differences~~.		Writes/reads the image's data to or from the specified streams. An image's stream representation is always run-length encoded, which is especially efficient in conjunction with temporal compression, i.e. sending sequences of difference images.

	==Properties==		==Properties==

Mellinger: /* Addition and Subtraction */

2008-09-12T14:20:04Z

Addition and Subtraction

← Older revision		Revision as of 14:20, 12 September 2008
Line 36:		Line 36:
	BitmapImage diff = image1 - image2;		BitmapImage diff = image1 - image2;
	diff += image2;		diff += image2;
	Note that pixels in difference images do not represent differences of individual color values; rather, difference images are computed by treating pixel values as signed 16-bit integers, and subtracting the second image's pixel data from the first ~~image~~'s.		Note that pixels in difference images do not represent differences of individual color values; rather, difference images are computed by treating pixel values as signed 16-bit integers, and subtracting the second image's pixel data from the first one's.

	==See also==		==See also==

Mellinger at 14:19, 12 September 2008

2008-09-12T14:19:37Z

New page

==Location==
<tt>src/shared/types</tt>

==Synopsis==
A <tt>BitmapImage</tt> object represents a 15-bit color pixel image, supporting the following operations:
*Manipulation of individual pixel values,
*Stream reading/writing in run-length compressed form,
*Addition/subtraction to support temporal compression of image sequences,
*Masked copying, using the otherwise unused 16th bit of the color value as a mask.

==Methods==
===BitmapImage(width=0, height=0)===
The constructor allocates storage for the specified dimensions, and initializes the image to black.
===SetBlack()===
Clears all pixels, setting them to black.
===SetBackground(BitmapImage)===
This function replaces an image's "background" with pixels from the image specified as argument. "Background" pixels are pixels with the most significant bit set to 1.
===WriteBinary(ostream), ReadBinary(istream)===
Writes/reads the image's data to or from the specified streams. An image's stream representation is always run-length encoded, which is especially efficient in conjunction with temporal compression, i.e. sending sequences of image differences.

==Properties==
===bool Empty (r)===
''True'' if at least one of the image's dimensions is 0.
===int Width, Height (r)===
The image's width and height in pixels.

==Pixel Access==
Access to individual pixels is provided via an index operator taking x and y coordinate as arguments:
BitmapImage myImage( 10, 10 );
myImage( 3, 4 ) = RGBColor::Red;
RGBColor myPixel = myImage( 5, 6 );

==Addition and Subtraction==
Difference images, and restoring original images from a reference frame followed with difference frames, is possible using addition and subtraction:
BitmapImage image1, image2;
BitmapImage diff = image1 - image2;
diff += image2;
Note that pixels in difference images do not represent differences of individual color values; rather, difference images are computed by treating pixel values as signed 16-bit integers, and subtracting the second image's pixel data from the first image's.

==See also==
[[Programming Reference:GraphDisplay Class]]

[[Category:Framework API]][[Category:Development]]