README
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imagetools
imageutil is a Go package that contains a seemingly random collection of low-level image processing tools. While the tools have been developed for a specific purpose, they are shared in the hope that others will find them useful.
Copyright and Licensing
This package is (C) Victor Costan 2015, and made available under the MIT
license, which is contained in the LICENSE file.
Documentation
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Overview ¶
Package imageutil is a collection of low-level image processing tools.
Index ¶
- func BuildRgbaMask(rgba uint32) uint64
- func CropRgba(rawImage []byte, width int, height int, xOffset int, yOffset int, xSize int, ...)
- func HashForRgbaFindCrop(needle []byte, needleWidth int, needleHeight int) uint32
- func MaskRgba(rawImage []byte, mask uint64)
- func ReadRgbaPng(fileName string) (*image.RGBA, error)
- func RgbPixelToHsl(red int, green int, blue int) (int, int, int)
- func RgbaCheckCrop(haystack []byte, hayWidth int, hayHeight int, needle []byte, needleWidth int, ...) bool
- func RgbaCheckMaskedCrop(haystack []byte, hayWidth int, hayHeight int, needle []byte, needleWidth int, ...) bool
- func RgbaDiffMaskedCrop(haystack []byte, hayWidth int, hayHeight int, needle []byte, needleWidth int, ...) int64
- func RgbaDiffThresholdCrop(haystack []byte, hayWidth int, hayHeight int, needle []byte, needleWidth int, ...) int
- func RgbaFindCrop(haystack []byte, hayWidth int, hayHeight int, needle []byte, needleWidth int, ...) (int, int, int)
- func RgbaFindMaskedCrop(haystack []byte, hayWidth int, hayHeight int, needle []byte, needleWidth int, ...) (int, int, int)
- func RgbaFindPillars(rgbaImage []byte, width int, height int, minRed int, maxRed int, minGreen int, ...)
- func RgbaFindPuddle(rgbaImage []byte, width int, height int, minRed int, maxRed int, minGreen int, ...) int
- func RgbaResetPuddles(rgbaImage []byte)
- func RgbaThreshold(rgbaImage []byte, minRed int, maxRed int, minGreen int, maxGreen int, ...)
- func RgbaToHsla(rgbaImage []byte, hslaImage []byte)
- func RgbaToPng(rawImage []byte, width int, height int, fileName string) error
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func BuildRgbaMask ¶
BuildMask computes a word mask from a 32-bit RGBA mask. The word mask is intended to be used with the MaskRgba function.
func CropRgba ¶
func CropRgba(rawImage []byte, width int, height int, xOffset int, yOffset int, xSize int, ySize int, target *[]byte)
CropRgba crops an RGBA image into a target slice. The target slice's length is set to the needed image length. If the slice's capacity is too small, the slice is re-created.
func HashForRgbaFindCrop ¶
HashForRgbaFindCrop computes the needle hash needed by RgbaFind. It returns the hash.
func MaskRgba ¶
MaskRgba applies a word mask to an RGBA image buffer. This uses fast 64-bit operations. In return for the speed, the caller must covert the RGBA mask into a word mask, with the help of BuildMask.
func ReadRgbaPng ¶
ReadRgbaPng decodes a PNG image from a file into a raw RGBA buffer. It returns the decoded image and any error encountered.
func RgbPixelToHsl ¶
RgbPixelToHsl returns the HSL values for a RGB color with 8-bits / channel. It is mostly useful for easy conversion to our custom HSL scheme where H is scaled between 0 and 255.
func RgbaCheckCrop ¶
func RgbaCheckCrop(haystack []byte, hayWidth int, hayHeight int, needle []byte, needleWidth int, needleHeight int, needleLeft int, needleTop int) bool
RgbaCheckCrop returns true if an image is a cropped version of another one. This is image pattern-matching, but only aligns the pattern with the image in one predetermined position.
func RgbaCheckMaskedCrop ¶
func RgbaCheckMaskedCrop(haystack []byte, hayWidth int, hayHeight int, needle []byte, needleWidth int, needleHeight int, needleLeft int, needleTop int, rgbaMask uint32) bool
RgbaCheckMaskedCrop checks if an image is a crop&mask from another image. This is image pattern-matching, but only aligns the pattern with the image in one predetermined position, and masks the image on the fly. The pattern is assumed to have already been masked.
func RgbaDiffMaskedCrop ¶
func RgbaDiffMaskedCrop(haystack []byte, hayWidth int, hayHeight int, needle []byte, needleWidth int, needleHeight int, needleLeft int, needleTop int, rgbaMask uint32) int64
RgbaDiffMaskedCrop diffs an image with a crop&mask of another image. It returns the sum of absolute pixel differences.
func RgbaDiffThresholdCrop ¶
func RgbaDiffThresholdCrop(haystack []byte, hayWidth int, hayHeight int, needle []byte, needleWidth int, needleHeight int, needleLeft int, needleTop int, minRed int, maxRed int, minGreen int, maxGreen int, minBlue int, maxBlue int) int
RgbaDiffThresholdCrop diffs an image with a crop&threshold of another image. It returns the sum of absolute pixel differences.
func RgbaFindCrop ¶
func RgbaFindCrop(haystack []byte, hayWidth int, hayHeight int, needle []byte, needleWidth int, needleHeight int, needleHash uint32, scratch []byte) (int, int, int)
RgbaFindCrop looks for a needle image in a hastack image. It returns the number of matches and the coordinates of the last match. The scratch space capacity must be at least 4 * hayWidth. The needle's hash can be computed by RgbaHashForFindCrop.
func RgbaFindMaskedCrop ¶
func RgbaFindMaskedCrop(haystack []byte, hayWidth int, hayHeight int, needle []byte, needleWidth int, needleHeight int, rgbaMask uint32, needleHash uint32, scratch []byte) (int, int, int)
RgbaFindMaskedCrop looks for a masked needle image in a hastack image. It returns the number of matches and the coordinates of the last match. The scratch space capacity must be at least 4 * hayWidth. The needle's hash can be computed by RgbaHashForFindCrop. The needle is assumed to have been masked before RgbaHashForFindCrop and this method are called.
func RgbaFindPillars ¶
func RgbaFindPillars(rgbaImage []byte, width int, height int, minRed int, maxRed int, minGreen int, maxGreen int, minBlue int, maxBlue int, pillars [][4]int32)
RgbaFindPillars returns the tallest vertical strips in an image.
func RgbaFindPuddle ¶
func RgbaFindPuddle(rgbaImage []byte, width int, height int, minRed int, maxRed int, minGreen int, maxGreen int, minBlue int, maxBlue int, startY int, puddlePixels [][2]int32) int
RgbaFindPuddle locates contiguous areas in an image. The image's A channel is (ab)used to track the image's visited areas. It returns the size of the area that it found.
func RgbaResetPuddles ¶
func RgbaResetPuddles(rgbaImage []byte)
RgbaResetPuddles resets the Alpha channel of all pixles to 255. This is useful after running puddle searches over an image.
func RgbaThreshold ¶
func RgbaThreshold(rgbaImage []byte, minRed int, maxRed int, minGreen int, maxGreen int, minBlue int, maxBlue int)
RgbaThreshold sets the alpha channel in image to a threshold function. The function is 1 when the R, G, and B values are between given amounts, and 0 otherwise.
func RgbaToHsla ¶
RgbaToHsla converts an RGBA image to a HSLA image. H, S, and L are in the range 0..255. A is unchanged. HSLA images can be used with most RGBA processing functions, like RgbaToPng.
Types ¶
This section is empty.
Source Files