YuImage

YuImage is a collection of image processing libraries, classes and functions for Delphi. In particular, it contains Delphi ports of the following C libraries, all with complete API, statically linked, and no DLLs needed:

Little CMS implements fast transformations between color profiels based on the International Color Consortium (ICC) 4.4 specification and support for all kinds of V2 and V4 profiles.

• Read and write ICC profiles.
• Create new or modify existing profiles.
• Apply profiles to a wide range of pixel formats.

libpng supports almost all features of the PNG image format, is extensible, and extensively tested.

• Read and write PNG images, both interlaced and non-interlaced..
• RGB, palette, and grayscale color types, with 1, 2, 4, 8, and 16-bit color depth with automatic conversion.
• Full alpha transparency.

TYuPngImage is an image class which descends from TGraphic. It loads and draws PNG encoded images with transparency and automatically applies embedded ICC color profiles, gamma correction, and chromaticities.

WebP is a modern image format that provides superior lossless and lossy image compression. It can create smaller and richer images. WebP lossless images are 26% smaller in size compared to PNGs. WebP lossy images are 25-34% smaller than comparable JPEG images at equivalent perceived quality.

• Decode and encode WebP images to RGB, BGR, and YUV.
• Demuxer to extract image and external format data from WebP images.
• Muxer to manipulate WebP containers with color profile, metadata and animation.
• Animatied WebP decoder and encoder.
• Multi-threading.
• Full alpha transparency.

TYuWebPImage is a TGraphic descendent image class. It loads and draws WebP encoded images with alpha transparency and automatically applies embedded ICC profiles. TYuWebPImage renders animated WebP images.

Demo projects, including an Image Viewer with thumbnails preview, are included in the download.

{ Add the YuPngImage and YuWebPImage units once to any uses clause to register 
  TYuPngImage as the PNG handler and TYuWebPImage as the WebP handler. }
uses
  Graphics,    // For TPicture.
  YuPngImage,  // Register TYuPngImage.
  YuWebPImage; // Register TYuWebPImage.
 
procedure LoadImages;
var
  pic: TPicture;
begin
  pic := TPicture.Create;
  try
    pic.LoadFromFile('test.png'); // Load a PNG image.
    { Add code here to do something with the picture. }
  finally
    pic.Free;
  end;
 
  pic := TPicture.Create;
  try
    pic.LoadFromFile('test.webp'); // Load a WebP image.
    { Add code here to do something with the picture. }
  finally
    pic.Free;
  end;
end;

Because TPngImage, Delphi's own PNG image class, if faulty. TYuPngImage fixes some annoying bugs and deficiencies of TPngImage, as demonstrated below.

The examples were painted by Delphi 11.2 Alexandria, the most recent Delphi at the time of this writing. The left and right images are drawn on a checker board pattern to show their transparent pixels. The center image points out pixel differences with a red color overlay.

• Embedded ICC color profiles go unnoticed in TPngImage. TYuPngImage reads the iCCP chunk and applies the proper color conversions. In this example, red and blue are swapped.
  

• In this example, failure to apply ICC color profiles leads to negative rendering of grayscale images. The correct gradient is white on the left and black on the right.
  

• Primary chromaticities and white point are not handled in TPngImage. TYuPngImage reads the cHRM chunk and applies the red, green, and blue chromaticities and the referenced white point. In this example, red and green are swapped.
  

• 2-bit grayscale images show wrong colors in TPngImage. The differences are in stainted shades of gray, whereas the lightest color should be a clean white.
  

• 2-bit grayscale can have 7 colors in TPngImage, where only 4 colors are possible. The artistic diff-pattern hints at an algorithmic problem. TYuPngImage is less imaginative and sticks the correct 4 colors.
  

• Transparency ignored for 16-bit grayscale in TPngImage so the checker board does not shine through.
  

• Transparency ignored for 16-bit color as well in TPngImage.
  

• Access Violation and memory leak on invalid IHDR data in TPngImage. Older Delphis are more prone to AV than newer ones, but even the current Delphi 11.2 Alexandria is affected. TYuPngImage issues a proper error message and does not leak memory, in all Delphi versions.
  

YuImage development uncovered a problem in Little CMS:

• Little CMS wrong black point compensation in case of matrix-shaper with inverted curves.