Data.Bitmap.Searchable

Documentation

class Bitmap bmp => BitmapSearchable bmp where

Class for searchable bitmaps

Using the functions of the Bitmap class, default functions are be defined for each of these; of course, implementations are free to define more efficient versions.

Methods

foldrCoords

Arguments

:: (Coordinates (BIndexType bmp) -> a -> a)

-> a

Starting value

-> Coordinates (BIndexType bmp)

Minimum, upper-left coordinates

-> Coordinates (BIndexType bmp)

Maximum, lower-right coordinates

-> bmp

The bitmap in which to scan coordinates

-> a

Recursively call a function with the coordinates, row by row from the left, from the minimum, upper-left coordinates to the maximum, lower-right coordinates

findPixel :: (BPixelType bmp -> Bool) -> bmp -> Maybe (Coordinates (BIndexType bmp))

Scan each pixel until a match is found in no particular order

Implementations are free to choose an efficient implementation that searches in a different direction from that of findPixelOrder. This function is often, but not necessarily always, the same as findPixelOrder.

findPixelOrder :: (BPixelType bmp -> Bool) -> bmp -> Coordinates (BIndexType bmp) -> Maybe (Coordinates (BIndexType bmp))

Scan each pixel, row by row from the left, starting at the given offset, until a match is found

findPixelEqual :: BPixelType bmp -> bmp -> Coordinates (BIndexType bmp) -> Maybe (Coordinates (BIndexType bmp))

A more restricted version of findPixelEqual that is usually more efficient when exact equality is desired

findPixels :: (BPixelType bmp -> Bool) -> bmp -> Coordinates (BIndexType bmp) -> [Coordinates (BIndexType bmp)]

findPixelsEqual :: BPixelType bmp -> bmp -> Coordinates (BIndexType bmp) -> [Coordinates (BIndexType bmp)]

findSubBitmap

Arguments

:: (BPixelType bmp -> BPixelType bmp -> Bool)

-> bmp

Super bitmap

-> bmp

Sub bitmap

-> Maybe (Coordinates (BIndexType bmp))

Search for coordinates where a sub-bitmap would match

Each coordinate, representing the upper-left-most corner, for which the sub-bitmap would fit is tried for a match until the function returns True for every pixel that is compared. The function is passed the pixel of the super bitmap which is searched as the first parameter, and the pixel of the sub bitmap is passed as the second parameter. Likewise, the super bitmap is then given to this function as the second parameter, and then the sub bitmap. Normally, the order in which the bitmap is checked in the same order as findPixelOrder, but implementation are free to implement this in whatever order is convenient or efficient; implementation should, however, assume that callers usually expect this order to be the most efficient one.

findSubBitmapOrder

Arguments

:: (BPixelType bmp -> BPixelType bmp -> Bool)

-> bmp

Super bitmap

-> bmp

Sub bitmap

-> Coordinates (BIndexType bmp)

-> Maybe (Coordinates (BIndexType bmp))

findSubBitmapEqual

Arguments

:: bmp

Super bitmap

-> bmp

Sub bitmap

-> Coordinates (BIndexType bmp)

-> Maybe (Coordinates (BIndexType bmp))

A more restricted version of findSubBitmapEqual that is usually more efficient when exact equality is desired

findSubBitmaps

Arguments

:: (BPixelType bmp -> BPixelType bmp -> Bool)

-> bmp

Super bitmap

-> bmp

Sub bitmap

-> Coordinates (BIndexType bmp)

-> [Coordinates (BIndexType bmp)]

findSubBitmapsEqual

Arguments

:: bmp

Super bitmap

-> bmp

Sub bitmap

-> Coordinates (BIndexType bmp)

-> [Coordinates (BIndexType bmp)]

findEmbeddedBitmap

Arguments

:: Integral i

=> [bmp]

-> bmp

Super bitmap

-> Coordinates (BIndexType bmp)

Coordinates relative to super bitmap

-> Maybe (i, bmp)

Find the first bitmap from the list that matches with the area of the same size from the given coordinate in the super bitmap (passed as the second argument) down-right (the coordinate is the first pixel which is the top-left most of the area to check). The match sub-bitmap and its index in the list are passed in the opposite order given in this description to the function, and the result is returned; if one is found. If no match is found, Nothing is returned.

The sub bitmaps are tested in order until a match is found, and if one is, its index in the list is returned. Each pixel in every sub bitmap is specially colored to represent a particular function. These colors are recognized:

• black / greatest intensity: the corresponding pixel in the super bitmap based on position can be any color. - white / least intensity: the corresponding pixel in the super bitmap must be the same color as every other pixel in the super bitmap that also corresponds to a white pixel.
• red FF0000 completely red: if there are white pixels in the sub bitmap, the corresponding pixel of the red pixel should be different from the color that corresponds to the white pixels.
• green 00FF00 complete green: if there are white pixels in the sub bitmap, the corresponding pixel of the green pixel should not be similar from the color that corresponds to the white pixels. See
• yellow FFFF00 complete yellow: if there are white pixels, this matches iff the color is similar to the colors that correspond to the white pixels.

areColorsSimilar to see whether two colors are considered to be similar.

The behaviour when any other pixel is encountered is undefined.

When the dimensions of a sub bitmap are too large for the super bitmap offset by the coordinates, where otherwise some pixels of the sub bitmap would not have any corresponding pixels in the super bitmap; then the sub bitmap simply does not match.

This function makes OCR with a known and static font more convenient to implement.

findEmbeddedBitmapString

Arguments

:: Integral i

=> ((i, bmp) -> a -> a)

-> a

-> [bmp]

-> bmp

Super bitmap

-> Coordinates (BIndexType bmp)

-> a

foldr equivalent of findEmbeddedBitmap for a horizontal string of embedded bitmaps

This is particularly convenient for OCR with a static and known font with multiple characters.

findFixedEmbeddedBitmapString

Arguments

:: Dimensions (Maybe (BIndexType bmp))

-> [bmp]

-> bmp

Super bitmap

-> Coordinates (BIndexType bmp)

-> Maybe (Coordinates (BIndexType bmp))

Scan for the given string of horizontally embedded bitmaps as in findEmbeddedBitmap

As with findEmbeddedBitmapString, each bitmap must be adjacent to match. If the integer is passed for a dimension ((width, height)), then no more than the value extra rows or columns will be checked. For example, if Just 0 is passed for the row value, then no additional rows will be checked.

Instances

Bitmap a => BitmapSearchable a

BitmapSearchable BitmapStringRGB24A4VR

BitmapSearchable BitmapStringRGB32

areColorsSimilar :: Pixel p => p -> p -> Bool

Binary similarity comparison

This function considers two colors to be similar if their difference according to the CIE94 algorithm (see colorDifferenceCIE94) is less than 23.

colorDifferenceCIE94 :: (Pixel p, RealFloat n, Ord n) => p -> p -> n

Approximate difference in color according to the CIE94 algorithm

defaultTransparentPixel :: Pixel p => p

Default transparent pixel value; FF007E

matchPixelAny :: Pixel p => p

matchPixelSame :: Pixel p => p

matchPixelSameThreshold :: Pixel p => p

matchPixelDif :: Pixel p => p

matchPixelDifThreshold :: Pixel p => p