images::ImageDither Class Reference

ImageDither. More...

#include <image_dither.h>

Public Member Functions
	ImageDither (void)
	~ImageDither (void)
void	dither_to_8bits (const BitmapAttributes *attrs_src, BitmapAttributes *attrs_dst)
	Convert and dither 32bits or 24bits true color image into 256 grayscale image.
Static Public Member Functions
static int	get_rowstride (int width, int bytes_per_pixel, int alignment)
	Get the rowstride.

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Detailed Description

ImageDither.

Definition at line 49 of file image_dither.h.

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Constructor & Destructor Documentation

images::ImageDither::ImageDither

(

void

)

Definition at line 39 of file image_dither.cpp.

References LOGPRINTF.

{
    LOGPRINTF("entry");
}

images::ImageDither::~ImageDither

(

void

)

Definition at line 44 of file image_dither.cpp.

References LOGPRINTF.

{
    LOGPRINTF("entry");
}

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Member Function Documentation

void images::ImageDither::dither_to_8bits	(	const BitmapAttributes *	attrs_src,
		BitmapAttributes *	attrs_dst
	)

Convert and dither 32bits or 24bits true color image into 256 grayscale image.

Parameters:

	attrs_src	in 32bits or 24bits
	attrs_dst	return in 256 grayscale

Definition at line 49 of file image_dither.cpp.

References images::BitmapAttributes::bytes_per_pixel, images::BitmapAttributes::data, get_rowstride(), images::BitmapAttributes::height, LOGPRINTF, images::BitmapAttributes::rowstride, and images::BitmapAttributes::width.

Referenced by images::TestImageDither::test().

{
    LOGPRINTF("entry %p, %p", attrs_src, attrs_dst);

    assert(attrs_src);
    assert(attrs_dst);
    assert(attrs_src->data);
    assert((attrs_src->bytes_per_pixel == 3) 
            || (attrs_src->bytes_per_pixel == 4));
    assert(attrs_src->rowstride >= 
            (attrs_src->width * attrs_src->bytes_per_pixel));
   
    attrs_dst->width = attrs_src->width;
    attrs_dst->height = attrs_src->height;
    attrs_dst->rowstride = get_rowstride(attrs_src->width, 1, 4);
    attrs_dst->bytes_per_pixel = 1;

    if (attrs_src->bytes_per_pixel == 4)
    {
        attrs_dst->data = dither_32bits_to_8bits(attrs_src->data, 
                                           attrs_src->width, 
                                           attrs_src->height, 
                                           attrs_src->rowstride);
    }
    else
    {
        attrs_dst->data = dither_24bits_to_8bits(attrs_src->data, 
                                           attrs_src->width, 
                                           attrs_src->height, 
                                           attrs_src->rowstride);
    }
}

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int images::ImageDither::get_rowstride	(	int	width,
		int	bytes_per_pixel,
		int	alignment
	)			[static]

Get the rowstride.

Parameters:

width

width of image

Returns:

rowstride

Definition at line 255 of file image_dither.cpp.

References LOGPRINTF.

Referenced by dither_to_8bits(), and images::ImagePage::estimate_length().

{
    LOGPRINTF("entry %d, %d, %d", width, bytes_per_pixel, alignment);

    int rowstride;

    int original_rowstride = width * bytes_per_pixel;
    if (original_rowstride % alignment)
    {
        int padding = alignment - (original_rowstride % alignment);
        rowstride = original_rowstride + padding;
    }
    else
    {
        rowstride = original_rowstride;
    }
    
    LOGPRINTF("return %d", rowstride);

    return rowstride;
}

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The documentation for this class was generated from the following files:

• image_dither.h
• image_dither.cpp