Safe Haskell | Safe-Infered |
---|
Main module exporting import/export functions into various image formats.
To use the library without thinking about it, look after decodeImage
and
readImage
.
Generally, the read* functions read the images from a file and try to decode it, and the decode* functions try to decode a bytestring.
For an easy image writing use the saveBmpImage
, saveJpgImage
& savePngImage
functions
- readImage :: FilePath -> IO (Either String DynamicImage)
- decodeImage :: ByteString -> Either String DynamicImage
- pixelMap :: forall a b. (Pixel a, Pixel b) => (a -> b) -> Image a -> Image b
- generateImage :: forall a. Pixel a => (Int -> Int -> a) -> Int -> Int -> Image a
- generateFoldImage :: forall a acc. Pixel a => (acc -> Int -> Int -> (acc, a)) -> acc -> Int -> Int -> (acc, Image a)
- saveBmpImage :: String -> DynamicImage -> IO ()
- saveJpgImage :: Int -> String -> DynamicImage -> IO ()
- savePngImage :: String -> DynamicImage -> IO ()
- class BmpEncodable pixel
- writeBitmap :: BmpEncodable pixel => FilePath -> Image pixel -> IO ()
- encodeBitmap :: forall pixel. BmpEncodable pixel => Image pixel -> ByteString
- readBitmap :: FilePath -> IO (Either String DynamicImage)
- decodeBitmap :: ByteString -> Either String DynamicImage
- encodeDynamicBitmap :: DynamicImage -> Either String ByteString
- writeDynamicBitmap :: FilePath -> DynamicImage -> IO (Either String Bool)
- readJpeg :: FilePath -> IO (Either String DynamicImage)
- decodeJpeg :: ByteString -> Either String DynamicImage
- encodeJpeg :: Image PixelYCbCr8 -> ByteString
- encodeJpegAtQuality :: Word8 -> Image PixelYCbCr8 -> ByteString
- class PngSavable a where
- encodePng :: Image a -> ByteString
- readPng :: FilePath -> IO (Either String DynamicImage)
- decodePng :: ByteString -> Either String DynamicImage
- writePng :: PngSavable pixel => FilePath -> Image pixel -> IO ()
- encodeDynamicPng :: DynamicImage -> Either String ByteString
- writeDynamicPng :: FilePath -> DynamicImage -> IO (Either String Bool)
- data Image a = Image {
- imageWidth :: !Int
- imageHeight :: !Int
- imageData :: Vector Word8
- data DynamicImage
- = ImageY8 (Image Pixel8)
- | ImageYA8 (Image PixelYA8)
- | ImageRGB8 (Image PixelRGB8)
- | ImageRGBA8 (Image PixelRGBA8)
- | ImageYCbCr8 (Image PixelYCbCr8)
- class Serialize a => Pixel a where
- canPromoteTo :: a -> PixelType -> Bool
- componentCount :: a -> Int
- pixelBaseIndex :: Image a -> Int -> Int -> Int
- mutablePixelBaseIndex :: MutableImage s a -> Int -> Int -> Int
- promotionType :: a -> PixelType
- pixelAt :: Image a -> Int -> Int -> a
- readPixel :: MutableImage s a -> Int -> Int -> ST s a
- writePixel :: MutableImage s a -> Int -> Int -> a -> ST s ()
- type Pixel8 = Word8
- data PixelYA8 = PixelYA8 !Word8 !Word8
- data PixelRGB8 = PixelRGB8 !Word8 !Word8 !Word8
- data PixelRGBA8 = PixelRGBA8 !Word8 !Word8 !Word8 !Word8
- data PixelYCbCr8 = PixelYCbCr8 !Word8 !Word8 !Word8
Generic functions
readImage :: FilePath -> IO (Either String DynamicImage)Source
Load an image file without even thinking about it, it does everything
as decodeImage
decodeImage :: ByteString -> Either String DynamicImageSource
If you want to decode an image in a bytestring without even thinking in term of format or whatever, this is the function to use. It will try to decode in each known format and if one decoding succeed will return the decoded image in it's own colorspace
pixelMap :: forall a b. (Pixel a, Pixel b) => (a -> b) -> Image a -> Image bSource
map
equivalent for an image, working at the pixel level.
Little example : a brightness function for an rgb image
brightnessRGB8 :: Int -> Image PixelRGB8 -> Image PixelRGB8 brightnessRGB8 add = pixelMap brightFunction where up v = fromIntegral (fromIntegral v + add) brightFunction (PixelRGB8 r g b) = PixelRGB8 (up r) (up g) (up b)
:: forall a . Pixel a | |
=> (Int -> Int -> a) | Generating function, with |
-> Int | Width in pixels |
-> Int | Height in pixels |
-> Image a |
Create an image given a function to generate pixels. The function will receive value from 0 to width-1 for the x parameter and 0 to height-1 for the y parameter. The coordinate 0,0 is the upper left corner of the image, and (width-1, height-1) the lower right corner.
for example, to create a small gradient image :
imageCreator :: String -> Image PixelRGB8 imageCreator path = writePng path $ generateImage pixelRenderer 250 300 where pixelRenderer x y = PixelRGB8 x y 128
:: forall a acc . Pixel a | |
=> (acc -> Int -> Int -> (acc, a)) | Function taking the state, x and y |
-> acc | Initial state |
-> Int | Width in pixels |
-> Int | Height in pixels |
-> (acc, Image a) |
This function implement the same algorithm as generateImage
,
and let use an user-defined state
Generic image writing
saveBmpImage :: String -> DynamicImage -> IO ()Source
Save an image to a '.bmp' file, will do everything it can to save an image.
saveJpgImage :: Int -> String -> DynamicImage -> IO ()Source
Save an image to a '.jpg' file, will do everything it can to save an image.
savePngImage :: String -> DynamicImage -> IO ()Source
Save an image to a '.png' file, will do everything it can to save an image. For example, a simple transcoder to png
transcodeToPng :: FilePath -> FilePath -> IO () transcodeToPng pathIn pathOut = do eitherImg <- decodeImage pathIn case eitherImg of Left _ -> return () Right img -> savePngImage img
Specific image format functions
Bitmap handling
class BmpEncodable pixel Source
All the instance of this class can be written as a bitmap file using this library.
writeBitmap :: BmpEncodable pixel => FilePath -> Image pixel -> IO ()Source
Write an image in a file use the bitmap format.
encodeBitmap :: forall pixel. BmpEncodable pixel => Image pixel -> ByteStringSource
Encode an image into a bytestring in .bmp format ready to be written on disk.
readBitmap :: FilePath -> IO (Either String DynamicImage)Source
Try to load a .bmp file. The colorspace would be RGB or RGBA
decodeBitmap :: ByteString -> Either String DynamicImageSource
Try to decode a bitmap image. Right now this function can output the following pixel types :
- PixelRGB8
encodeDynamicBitmap :: DynamicImage -> Either String ByteStringSource
Encode a dynamic image in bmp if possible, supported pixel type are :
- RGB8
- RGBA8
- Y8
writeDynamicBitmap :: FilePath -> DynamicImage -> IO (Either String Bool)Source
Write a dynamic image in a .bmp image file if possible. The same restriction as encodeDynamicBitmap apply.
Jpeg handling
readJpeg :: FilePath -> IO (Either String DynamicImage)Source
Try to load a jpeg file and decompress. The colorspace is still
YCbCr if you want to perform computation on the luma part. You can
convert it to RGB using colorSpaceConversion
decodeJpeg :: ByteString -> Either String DynamicImageSource
Try to decompress a jpeg file and decompress. The colorspace is still
YCbCr if you want to perform computation on the luma part. You can
convert it to RGB using colorSpaceConversion
This function can output the following pixel types :
- PixelY8
- PixelYCbCr8
encodeJpeg :: Image PixelYCbCr8 -> ByteStringSource
Encode an image in jpeg at a reasonnable quality level.
If you want better quality or reduced file size, you should
use encodeJpegAtQuality
:: Word8 | Quality factor |
-> Image PixelYCbCr8 | Image to encode |
-> ByteString | Encoded JPEG |
Function to call to encode an image to jpeg. The quality factor should be between 0 and 100 (100 being the best quality).
Png handling
class PngSavable a whereSource
Encode an image into a png if possible.
encodePng :: Image a -> ByteStringSource
Transform an image into a png encoded bytestring, ready to be writte as a file.
readPng :: FilePath -> IO (Either String DynamicImage)Source
Helper function trying to load a png file from a file on disk.
decodePng :: ByteString -> Either String DynamicImageSource
Transform a raw png image to an image, without modifying the underlying pixel type. If the image is greyscale and < 8 bits, a transformation to RGBA8 is performed. This should change in the future. The resulting image let you manage the pixel types.
This function can output the following pixel types :
- PixelY8
- PixelYA8
- PixelRGB8
- PixelRGBA8
writePng :: PngSavable pixel => FilePath -> Image pixel -> IO ()Source
Helper function to directly write an image as a png on disk.
encodeDynamicPng :: DynamicImage -> Either String ByteStringSource
Encode a dynamic image in bmp if possible, supported pixel type are :
- Y8
- YA8
- RGB8
- RGBA8
writeDynamicPng :: FilePath -> DynamicImage -> IO (Either String Bool)Source
Write a dynamic image in a .png image file if possible. The same restriction as encodeDynamicPng apply.
Image types and pixel types
Image
Image or pixel buffer, the coordinates are assumed to start from the upper-left corner of the image, with the horizontal position first, then the vertical one.
Image | |
|
data DynamicImage Source
Type allowing the loading of an image with different pixel structures
ImageY8 (Image Pixel8) | A greyscale image. |
ImageYA8 (Image PixelYA8) | An image in greyscale with an alpha channel. |
ImageRGB8 (Image PixelRGB8) | An image in true color. |
ImageRGBA8 (Image PixelRGBA8) | An image in true color and an alpha channel. |
ImageYCbCr8 (Image PixelYCbCr8) | An image in the colorspace used by Jpeg images. |
Pixels
class Serialize a => Pixel a whereSource
Typeclass used to query a type about it's properties regarding casting to other pixel types
canPromoteTo :: a -> PixelType -> BoolSource
Tell if a pixel can be converted to another pixel,
the first value should not be used, and undefined
can
be used as a valid value.
componentCount :: a -> IntSource
Return the number of component of the pixel
pixelBaseIndex :: Image a -> Int -> Int -> IntSource
Calculate the index for the begining of the pixel
mutablePixelBaseIndex :: MutableImage s a -> Int -> Int -> IntSource
Calculate theindex for the begining of the pixel at position x y
promotionType :: a -> PixelTypeSource
Return the constructor associated to the type, again the value in the first parameter is not used, so you can use undefined
pixelAt :: Image a -> Int -> Int -> aSource
Extract a pixel at a given position, (x, y), the origin is assumed to be at the corner top left, positive y to the bottom of the image
readPixel :: MutableImage s a -> Int -> Int -> ST s aSource
Same as pixelAt but for mutable images.
writePixel :: MutableImage s a -> Int -> Int -> a -> ST s ()Source
Write a pixel in a mutable image at position x y
Pixel type storing Luminance (Y) and alpha information on 8 bits. Value are stored in the following order :
- Luminance
- Alpha
Pixel type storing classic pixel on 8 bits Value are stored in the following order :
- Red
- Green
- Blue
data PixelRGBA8 Source
Pixel type storing a classic pixel, with an alpha component. Values are stored in the following order
- Red
- Green
- Blue
- Alpha
PixelRGBA8 !Word8 !Word8 !Word8 !Word8 |
data PixelYCbCr8 Source
Pixel storing data in the YCbCr colorspace, value are stored in the following order :
- Y (luminance)
- Cr
- Cb