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image is a Dart library providing the ability to load, save and manipulate images in a variety of different file formats.

The image library has no dependencies on dart:io or dart:html, so you can use the library for both server and web applications.

Supported Image Formats:

Read/Write:

• PNG / Animated APNG
• JPEG
• Targa
• GIF / Animated GIF

Read Only:

• WebP / Animated WebP
• TIFF
• Photoshop PSD
• OpenEXR

API

Examples

Filter Test

Format Decoding Functions

The following functions provide a high level interface for decoding images. You can also use the format specific Decoder classes to access format-specific data.

Generic Decoding Function

• Image decodeImage(List<int> bytes);
  Decode an image, determining the format of the file by analyzing the bytes. If the file is an animated image, the first frame is decoded. Note: because this function has to determine the format of the image before it can decode it, it is preferable to use a format specific decoding function, such as decodeJpg, if you know what the format is.
  

  • bytes: The contents of the image file.
    Returns: the decoded Image.

• Animation decodeAnimation(List<int> bytes);
  Decode a potentially animated image, determining the format of the file by analyzing the bytes. If the image isn't animated (a JPEG image, a non-animated GIF, etc), the returned Animation will contain a single frame containing the decoded image.
  

  • bytes: The contents of the image file.
    Returns: the decoded Animation.

• Image decodeNamedImage(List<int> bytes, String name);
  Identify the format of the image using the file extension provided by [name], and decode it with the appropriate decoder. For example, decodeNamedImage(imageData, 'image.jpg') will decode the image as a Jpeg.
  

  • bytes: The contents of the image file.
    
  • name: The name of the file (used to identify format from the file extension). Returns the decoded Image.

• Decoder findDecoderForData(List bytes);

_Returns the Decoder that can decode the given image data._
- **bytes**: The contents of the image file.

Format-Specific Decoding Functions

• Image decodeJpg(List<int> bytes);
  Decode a JPEG formatted image.
  

  • bytes: The contents of the JPEG file.
    Returns: the decoded Image.

• Image decodePng(List<int> bytes);
  Decode a PNG formatted image. If the PNG is animated, the first frame is decoded.
  

  • bytes: The contents of the PNG file.
    Returns: the decoded Image.

• Animation decodePngAnimation(List<int> bytes);
  Decode a PNG formatted animation. If the PNG isn't animated, the animation will contain a single frame with the PNG's image.
  

  • bytes: The contents of the PNG file.
    Returns: the decoded Animation.

• Image decodeGif(List<int> bytes);
  Decode a GIF formatted image. If the GIF is animated, the first frame is returned.
  

  • bytes: The contents of the GIF file.
    Returns: the decoded Image.

• Animation decodeGifAnimation(List<int> bytes);
  Decode an animated GIF file. If the GIF isn't animated, the animation will contain a single frame with the GIF's image.
  

  • bytes: The contents of the GIF file.
    Returns: the decoded Animation.

• Image decodePsd(List<int> bytes);
  Decode a Photoshop PSD formatted image.
  

  • bytes: The contents of the PSD file.
    Returns: the decoded Image.

• Image decodeTga(List<int> bytes);
  Decode a Targa formatted image.
  

  • bytes: The contents of the TGA file.
    Returns: the decoded Image.

• Image decodeWebP(List<int> bytes);
  Decode a WebP formatted image. If the WebP is animated ,the first frame is decoded.
  

  • bytes: The contents of the WebP file.
    Returns: the decoded Image.

• Animation decodeWebPAnimation(List<int> bytes);
  Decode an animated WebP file. If the WebP isn't animated, the animation will contain a single frame with the WebP image.
  

  • bytes: The contents of the WebP file.
    Returns: the decoded Animation.

• Image decodeExr(List<int> bytes, {double exposure = 1.0});
  Decode an OpenEXR formatted image, tone-mapped using the given exposure to a low dynamic range image.
  

  • bytes: The contents of the EXR file.
    Returns: the decoded Image.

• Image decodeTiff(List<int> bytes);
  Decode a TIFF formatted image.
  

  • bytes: The contents of the TIFF file.
    Returns: the decoded Image.

• Animation decodeTiffAnimation(List<int> bytes);
  Decode a multi-image TIFF file. If the TIFF doesn't have multiple images, the animation will contain a single image.
  

  • bytes: The contents of the TIFF file.
    Returns: the decoded Animation.

Format Encoding Functions

Generic Encoding Functions

• List<int> encodeNamedImage(Image image, String name);
  Identify the format of the image and encode it with the appropriate encoder.
  
  • image: The image to encode.
    
  • name: The name of the image, used to derive the format to encode with from the extension.
    Returns: the encoded bytes.

Format-Specific Encoding Functions

• List<int> encodeGif(Image image);
  Encode an image with the GIF format.
  

  • image: The image to encode.
    Returns: the encoded bytes.

• List<int> encodeGifAnimation(Animation image);
  Encode an animation with the animated GIF format.
  

  • image: The animation to encode.
    Returns: the encoded bytes.

• List<int> encodeJpg(Image image, {int quality: 100});
  Encode an image with the JPEG format.
  

  • image: The image to encode.
    
  • quality: The JPEG quality, in the range [0, 100] where 100 is highest quality.
    Returns: the encoded bytes.

• List<int> encodePng(Image image, {int level: 6});
  Encode an image with the PNG format.
  

  • image: The image to encode.
    
  • level: The compression level, in the range [0, 9] where 9 is the most compressed.
    Returns: the encoded bytes.

• List<int> encodeTga(Image image);
  Encode an image with the Targa format.
  

  • image: The image to encode.
    Returns: the encoded bytes.

Font / String Drawing Functions

• Image drawChar(Image dst, BitmapFont font, int x, int y, String string, {int color: 0xffffffff});
  Draw a single character with the given font.
  Returns the modified image.

• Image drawString(Image image, BitmapFont font, int x, int y, String string, {int color: 0xffffffff});
  Draw the string with the given font.
  Returns the modified image.
  Example, draw the string "Hello" starting at pixel 50,50, using the built-in 24-pt Arial font:
  drawString(image, arial_24, 50, 50, "Hello");
  

• BitmapFont readFontZip(List<int> bytes);
  Load a BitmapFont from a zip file.
  Returns the decoded font.

• BitmapFont readFont(String fnt, Image page);
  Load a BitmapFont from a font file and image.
  Returns the decoded font.

Image Filter / Modification Functions

Most filter functions modify images in-place, and return that image to make chaining functions easier. A few functions work on a copy of the input image, returning the modified copy. Those functions will be prefixed with the name 'copy'.

• Image adjustColor(Image src, {int blacks, int whites, int mids, double contrast, double saturation, double brightness, double gamma, double exposure, double hue, double amount});
  Adjust the color of the [src] image using various color transformations.
  

  • src: The image to modify.
    
  • blacks: [todo document]
    
  • whites: [todo document]
    
  • mids: [todo document]
    
  • contrast: [todo document]
    
  • saturation: Scale the saturation of the image, where saturation 1.0 is the fully saturated color and saturation 0.0 is fully unsaturated (grayscale) color.
    
  • brightness: A linear multiplier for the RGB color values, brightens (> 1) or dims (< 0) the image. Default: 1.0.
    
  • exposure: an exponential multiplier for the RGB color values, as RGB *= pow(2, exposure). Default: 1.0.
    
  • gamma: An exponential multiplier for the RGB color values, as RGB = pow(RGB, gamma). A gamma > 1 darkens the image, and gamma < 1 brightens the image. Default: 1.0
    
  • hue: Offset the hue of the image, specified in degrees in the range [0, 360]. Default: 0.0
    
  • amount: The strength that this filter is applied to the image, where 1.0 indicates the filter has full effect, and 0.0 has no effect (the original image is returned unmodified). Default: 1.0.
    Returns: The modified [src] image.
    

• Image brightness(Image src, int brightness);
  Adjust the brightness of the image (in place).
  Returns the modified image.
  

• Image bumpToNormal(Image src, {num strength = 2.0});
  Generate a normal map from a height-field bump image.
  Returns a new image.
  

• Image colorOffset(Image src, {int red = 0, int green = 0, int blue = 0, int alpha = 0}) {;
  Apply an offset to the colors of the image (in place).
  Returns the modified image.
  

• Image contrast(Image src, num contrast);
  Apply the Contrast convolution filter to the image (in place).
  Returns the modified image.
  

• Image convolution(Image src, List<num> filter, {num div = 1.0, num offset = 0.0});
  Apply a convolution filter to the image (in place).
  Returns the modified image.
  

• Image copyCrop(Image src, int x, int y, int w, int h);
  Create a cropped copy of the image.
  Returns a new image.
  

• Image copyInto(Image dst, Image src, {int dstX, int dstY, int srcX, int srcY, int srcW, int srcH, bool blend = true});
  Copy an area of the src image into dst.
  Returns the modified dst image.
  

• Image copyRectify(Image src, {Point topLeft, Point topRight, Point bottomLeft, Point bottomRight, Image toImage});
  Returns a copy of the [src] image, where the given rectangle has been mapped to the full image.
  

• Image copyResize(Image src, {int width, int height, Interpolation interpolation = Interpolation.nearest});
  Create a resized copy of the image.
  If width or height are -1, it will be calculated by maintaining the aspect ratio of the original image.
  Interpolation: nearest, linear, cubic
  Returns a new image.
  

• Image copyResizeCropSquare(Image src, int size);
  Returns a resized and square cropped copy of the [src] image of [size] size.
  

• Image copyRotate(Image src, num angle, {Interpolation interpolation = Interpolation.nearest});
  Returns a copy of the [src] image, rotated by [angle] degrees.
  Returns a new image.
  

• Image drawCircle(Image image, int x0, int y0, int radius, int color);
  Draw a circle (in place).
  Returns the modified image.
  

• Image drawImage(Image dst, Image src, {int dstX, int dstY, int srcX, int srcY, int srcW, int srcH, bool blend = true});
  Draw the src image onto dst.
  Returns the modified dst image.
  

• Image drawLine(Image image, int x1, int y1, int x2, int y2, int color, {bool antialias = false, num thickness = 1});
  Draw a line (in place).
  Returns the modified image.
  

• Image drawPixel(Image image, int x, int y, int color, [int opacity = 0xff]);
  Draw a single pixel into the image, applying alpha and opacity blending (in place).
  Returns the modified image.
  

• Image drawRect(Image image, int x1, int y1, int x2, int y2, int color);
  Draw a rectangle (in place).
  Returns the modified image.
  

• Image dropShadow(Image src, int hshadow, int vshadow, int blur, {int shadowColor = 0x000000a0});
  Create a drop-shadow effect.
  Returns a new image.
  

• Image emboss(Image src);
  Apply the Emboss convolution filter (in place).
  Returns the modified image.
  

• Image fill(Image image, int color);
  Fill the image with the given color (in place).
  Returns the modified image.
  

• Image fillFlood(Image src, int x, int y, int color, {num threshold = 0.0, bool compareAlpha = false});
  Fill the 4-connected shape containing [x],[y] in the image [src] with the given [color].
  Returns the modified image.
  

• Image fillRect(Image src, int x1, int y1, int x2, int y2, int color);
  Fill a rectangle with the given color (in place).
  Returns the modified image.
  

• List<int> findTrim(Image src, {int mode = TRIM_TRANSPARENT, sides = TRIM_ALL});
  Find the crop area to be used by the trim function.
  Returns the coordinates as [x, y, width, height].
  

• Image flip(Image src, Flip mode);
  Flip the image with Flip.horizontal, Flip.vertical, or Flip.both (in place).
  Returns the modified image.
  

• Image gaussianBlur(Image src, int radius);
  Blur the image (in place).
  Returns the modified image.
  

• Image grayscale(Image src);
  Convert the colors of the image to grayscale (in place).
  Returns the modified image.
  

• Image invert(Image src);
  Invert the colors of the image (in place).
  Returns the modified image.
  

• Image noise(Image image, double sigma, {NoiseType type = NoiseType.gaussian, math.Random random});
  Add random noise to pixel values (in place).
  Returns the modified image.
  

• Image normalize(Image src, int minValue, int maxValue);
  Linearly normalize the pixel values of the image (in place).
  Returns the modified image.
  

• Image pixelate(Image src, int blockSize, {PixelateMode mode = PixelateMode.upperLeft});
  Pixelate the [src] image. [blockSize] determines the size of the pixelated blocks. If [mode] is [PixelateMode.upperLeft] then the upper-left corner of the block will be used for the block color. Otherwise if [mode] is [PixelateMode.average], the average of all the pixels in the block will be used for the block color.
  Returns the modified image.
  

• Image quantize(Image src, {int numberOfColors = 256, QuantizeMethod method = QuantizeMethod.neuralNet});
  Reduces the number of colors in the image to the given amount.
  Returns the modified image.
  

• Image remapColors(Image src, { Channel red = Channel.red, Channel green = Channel.green, Channel blue = Channel.blue, Channel alpha = Channel.alpha});
  Remap the color channels of the image. [red], [green], [blue] and [alpha] should be set to one of the following: [Channel.red], [Channel.green], [Channel.blue], [Channel.alpha], or [Channel.luminance]. For example, remapColors(src, red: Channel.green, green: Channel.red) will swap the red and green channels of the image. remapColors(src, alpha: Channel.luminance) will set the alpha channel to the luminance (grayscale) of the image..
  Returns the modified image.
  

• Image sepia(Image src, {num amount: 0.8});
  Filter the image colors using sepia tone.
  Returns the modified image.
  

• Image smooth(Image src, num w);
  Apply a smooth convolution filter to the image (in place).
  Returns the modified image.
  

• Image sobel(Image src, {double amount: 1.0});
  Apply a sobel edge detection filter to the image (in place).
  

  • amount: The strength that this filter is applied to the image, where 1.0 indicates the filter has full effect, and 0.0 has no effect (the original image is returned unmodified). Default: 1.0.
    Returns: The modified [src] image.
    

• Image vignette(Image src, {num start: 0.3, num end: 0.8, num amount: 0.8});
  Darkens the edges of the image using a elliptical vignette filter.
  Returns the modified image.