Create an image with VU (Vector Unboxed) representation and pixels of Double precision. Note, that for Double precision pixels it is essential to keep values normalized in the [0, 1] range in order for an image to be written to file properly.

>>> let grad_gray = makeImage (200, 200) (\(i, j) -> PixelY (fromIntegral i)/200 * (fromIntegral j)/200)

Because all Pixels and Images are installed into Num, above is equivalent to:

>>> let grad_gray = makeImage (200, 200) (\(i, j) -> PixelY $ fromIntegral (i*j)) / (200*200)
>>> writeImage "images/grad_gray.png" grad_gray

Creating color images is just as easy.

>>> let grad_color = makeImage (200, 200) (\(i, j) -> PixelRGB (fromIntegral i) (fromIntegral j) (fromIntegral (i + j))) / 400
>>> writeImage "images/grad_color.png" grad_color

Construct an image from a nested rectangular shaped list of pixels. Length of an outer list will constitute m rows, while the length of inner lists - n columns. All of the inner lists must be the same length and greater than 0.

>>> fromLists [[PixelY (fromIntegral (i*j) / 60000) | j <- [1..300]] | i <- [1..200]]
<Image VectorUnboxed Y (Double): 200x300>

Read image as luma (brightness).

Read image as luma with Alpha channel.

Read image in RGB colorspace.

Read image in RGB colorspace with Alpha channel.

This function allows for reading any supported image in the exact colorspace and precision it is currently encoded in. For instance, frog image can be read into it's YCbCr colorspace with Word8 precision and into any supported array representation.

>>> readImageExact JPG "images/frog.jpg" :: IO (Either String (Image RP YCbCr Word8))
Right <Image RepaParallel YCbCr (Word8): 200x320>

The drawback here is that colorspace and precision has to match exactly, otherwise it will return an error:

>>> readImageExact JPG "images/frog.jpg" :: IO (Either String (Image RD RGB Word8))
Left "JuicyPixel decoding error: Input image is in YCbCr8 (Pixel YCbCr Word8), cannot convert it to RGB8 (Pixel RGB Word8) colorspace."

Attempt to read an image in a particular color space that is not supported by the format, will result in a compile error. Refer to Readable class for all images that can be decoded.

Just like readImage, this function will guess an output file format from the extension and write to file any image that is in one of Y, YA, RGB or RGBA ColorSpaces with Double precision. While doing necessary conversions the choice will be given to the most suited color space supported by the format, for instance, in case of a PNG format, an (Image arr RGBA Double) would be written as RGBA16, hence preserving transparency and using highest supported precision Word16. At the same time, writing that image in GIF format would save it in RGB8, since Word8 is the highest precision GIF supports and it currently cannot be saved with transparency.

Write an image in a specific format, while supplying any format specific options. Precision and color space that an image will be written is decided from image's type. Attempt to write image file in a format that does not support color space and precision combination will result in a compile error.

Makes a call to the current display program, which can be changed using setDisplayProgram. An image is written as a .tiff file into an operating system's temporary directory and passed as an argument to the display program. If a blocking flag was set to False using setDisplayProgram, then function will return immediately with (Just ThreadId), otherwise it will block current thread until external program is terminated, in which case Nothing is returned. Temporary file is deleted, after a program displaying an image is closed.

>>> frog <- readImageRGB "images/frog.jpg"
>>> displayImage frog
Just ThreadId 505
>>> setDisplayProgram ("gimp", True)
>>> displayImage frog -- will only return after gimp is closed.
Nothing

Get the number of rows in an image.

>>> frog <- readImageRGB "images/frog.jpg"
>>> frog
<Image VectorUnboxed RGB (Double): 200x320>
>>> rows frog
200

Get the number of columns in an image.

>>> frog <- readImageRGB "images/frog.jpg"
>>> frog
<Image VectorUnboxed RGB (Double): 200x320>
>>> cols frog
320

Get dimensions of an image.

>>> frog <- readImageRGB "images/frog.jpg"
>>> frog
<Image VectorUnboxed RGB (Double): 200x320>
>>> dims frog
(200,320)

Get a pixel at i-th and j-th location.

>>> let grad_gray = makeImage (200, 200) (\(i, j) -> PixelY $ fromIntegral (i*j)) / (200*200)
>>> index grad_gray (20, 30) == PixelY ((20*30) / (200*200))
True

Image indexing function that returns a default pixel if index is out of bounds.

Image indexing function that returns Nothing if index is out of bounds, Just pixel otherwise.

Map a function over a an image.

Map an index aware function over each pixel in an image.

Zip two images with a function

Zip two images with an index aware function

Traverse an image

Traverse two images.

Transpose an image

Backwards permutation of an image.

Perform matrix multiplication on two images. Inner dimensions must agree.

Undirected reduction of an image.

Sum all pixels in the image.

Multiply all pixels in the image.

Retrieve the biggest pixel from an image

Retrieve the smallest pixel from an image

Scales all of the pixels to be in the range [0, 1].

Exchange the underlying array representation of an image.

Unboxed Vector representation.

Repa Delayed Array representation, which allows for fusion of computation.

Repa Unboxed Array representation, which is computed sequentially.

Repa Unboxed Array representation, which is computed in parallel.