Safe Haskell	None
Language	Haskell2010

Codec.Picture.Jpg

Description

Module used for JPEG file loading and writing.

Synopsis

decodeJpeg :: ByteString -> Either String DynamicImage
decodeJpegWithMetadata :: ByteString -> Either String (DynamicImage, Metadatas)
encodeJpegAtQuality :: Word8 -> Image PixelYCbCr8 -> ByteString
encodeJpegAtQualityWithMetadata :: Word8 -> Metadatas -> Image PixelYCbCr8 -> ByteString
encodeDirectJpegAtQualityWithMetadata :: forall px. JpgEncodable px => Word8 -> Metadatas -> Image px -> ByteString
encodeJpeg :: Image PixelYCbCr8 -> ByteString
class (Pixel px, PixelBaseComponent px ~ Word8) => JpgEncodable px

Documentation

decodeJpeg :: ByteString -> Either String DynamicImage Source #

Try to decompress and decode a jpeg file. The colorspace is still YCbCr if you want to perform computation on the luma part. You can convert it to RGB using convertImage from the ColorSpaceConvertible typeclass.

This function can output the following images:

decodeJpegWithMetadata :: ByteString -> Either String (DynamicImage, Metadatas) Source #

Equivalent to decodeJpeg but also extracts metadatas.

Extract the following metadatas from the JFIF block:

DpiX
DpiY

Exif metadata are also extracted if present.

encodeJpegAtQuality Source #

Arguments

:: 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).

encodeJpegAtQualityWithMetadata Source #

Arguments

:: Word8	Quality factor
-> Metadatas
-> Image PixelYCbCr8	Image to encode
-> ByteString	Encoded JPEG

Equivalent to encodeJpegAtQuality, but will store the following metadatas in the file using a JFIF block:

DpiX
DpiY

encodeDirectJpegAtQualityWithMetadata Source #

Arguments

:: forall px. JpgEncodable px
=> Word8	Quality factor
-> Metadatas
-> Image px	Image to encode
-> ByteString	Encoded JPEG

Equivalent to encodeJpegAtQuality, but will store the following metadatas in the file using a JFIF block:

DpiX
DpiY

This function also allow to create JPEG files with the following color space:

Y (Pixel8) for greyscale.
RGB (PixelRGB8) with no color downsampling on any plane
CMYK (PixelCMYK8) with no color downsampling on any plane

encodeJpeg :: Image PixelYCbCr8 -> ByteString Source #

Encode an image in jpeg at a reasonnable quality level. If you want better quality or reduced file size, you should use encodeJpegAtQuality

class (Pixel px, PixelBaseComponent px ~ Word8) => JpgEncodable px Source #

Helper type class describing all JPG-encodable pixel types

Minimal complete definition

componentsOfColorSpace, encodingState, scanSpecificationOfColorSpace

Instances

Instances details

JpgEncodable PixelCMYK8 Source #
Instance details Defined in Codec.Picture.Jpg Methods additionalBlocks :: Image PixelCMYK8 -> [JpgFrame] componentsOfColorSpace :: Image PixelCMYK8 -> [JpgComponent] encodingState :: Int -> Image PixelCMYK8 -> Vector EncoderState imageHuffmanTables :: Image PixelCMYK8 -> [(JpgHuffmanTableSpec, HuffmanPackedTree)] scanSpecificationOfColorSpace :: Image PixelCMYK8 -> [JpgScanSpecification] quantTableSpec :: Image PixelCMYK8 -> Int -> [JpgQuantTableSpec] maximumSubSamplingOf :: Image PixelCMYK8 -> Int
JpgEncodable PixelYCbCr8 Source #
Instance details Defined in Codec.Picture.Jpg Methods additionalBlocks :: Image PixelYCbCr8 -> [JpgFrame] componentsOfColorSpace :: Image PixelYCbCr8 -> [JpgComponent] encodingState :: Int -> Image PixelYCbCr8 -> Vector EncoderState imageHuffmanTables :: Image PixelYCbCr8 -> [(JpgHuffmanTableSpec, HuffmanPackedTree)] scanSpecificationOfColorSpace :: Image PixelYCbCr8 -> [JpgScanSpecification] quantTableSpec :: Image PixelYCbCr8 -> Int -> [JpgQuantTableSpec] maximumSubSamplingOf :: Image PixelYCbCr8 -> Int
JpgEncodable PixelRGB8 Source #
Instance details Defined in Codec.Picture.Jpg Methods additionalBlocks :: Image PixelRGB8 -> [JpgFrame] componentsOfColorSpace :: Image PixelRGB8 -> [JpgComponent] encodingState :: Int -> Image PixelRGB8 -> Vector EncoderState imageHuffmanTables :: Image PixelRGB8 -> [(JpgHuffmanTableSpec, HuffmanPackedTree)] scanSpecificationOfColorSpace :: Image PixelRGB8 -> [JpgScanSpecification] quantTableSpec :: Image PixelRGB8 -> Int -> [JpgQuantTableSpec] maximumSubSamplingOf :: Image PixelRGB8 -> Int
JpgEncodable Pixel8 Source #
Instance details Defined in Codec.Picture.Jpg Methods additionalBlocks :: Image Pixel8 -> [JpgFrame] componentsOfColorSpace :: Image Pixel8 -> [JpgComponent] encodingState :: Int -> Image Pixel8 -> Vector EncoderState imageHuffmanTables :: Image Pixel8 -> [(JpgHuffmanTableSpec, HuffmanPackedTree)] scanSpecificationOfColorSpace :: Image Pixel8 -> [JpgScanSpecification] quantTableSpec :: Image Pixel8 -> Int -> [JpgQuantTableSpec] maximumSubSamplingOf :: Image Pixel8 -> Int