SharpAstro.Tga 3.32.1561

SharpAstro.Tga

Pure-managed Truevision TGA 2.0 reading for .NET 10, written from the Truevision TGA File Format Specification, plus a writer for 24-bit and 32-bit true colour (see "Writing" below).

Supported: colour-mapped, true-colour and greyscale images (types 1, 2, 3), raw or run-length coded (types 9, 10, 11); 8, 15, 16, 24 and 32-bit pixels; 8, 15, 16, 24 and 32-bit colour-map entries; alpha from 32-bit pixels or from the descriptor's attribute bit on 15/16-bit ones; both vertical origins and both horizontal directions. The image ID is skipped. Output is always tightly packed, top-down RGBA8.

using SharpAstro.Tga;

byte[] data = File.ReadAllBytes("image.tga");
TgaImage image = TgaReader.Decode(data);
Console.WriteLine($"{image.Width} × {image.Height}, alpha: {image.HasAlpha}");
byte[] rgba = image.Rgba;

TgaReader.TryReadInfo checks the header without decoding.

The reader refuses with InvalidDataException rather than guessing: a truncated file, an RLE packet running past the end of the image, an unknown image type or depth, a colour index outside the map, a non-zero interleave field, and more than 67,108,864 declared pixels (checked before anything is allocated). Not read: the extension and developer areas, so the "attributes type" byte is not consulted. 16-bit greyscale (grey + alpha) is refused, because the specification does not define it and ImageMagick reads it differently from stb_image.

Every pixel the reader produces is compared byte for byte against ImageMagick's read of the same file in the test suite.

Writing

byte[] tga = TgaWriter.EncodeRgba8(rgba, width, height, new TgaWriteOptions { Rle = true });
byte[] tga24 = TgaWriter.EncodeRgb8(rgb, width, height);

24-bit (EncodeRgb8) and 32-bit (EncodeRgba8, 8 attribute bits) true colour, raw (type 2) or run-length coded (type 10), top-left origin by default (TopOrigin = false for bottom-left). Every file ends with the TGA 2.0 footer (TRUEVISION-XFILE. and a zero byte). RLE packets never cross a scanline, as the specification asks. A wrong buffer length or a dimension outside 1..65535 is an ArgumentException.