Operations Reference

Complete catalogue of transformations and filters available on ImagePipeline. All operations modify the pipeline in place and return this for chaining.

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Transformations

Resize(width, height, filter)

Resize to exact dimensions. Does not preserve aspect ratio — if the ratio differs from the source, the image is stretched.

pipe.Resize(800, 600, ResizeFilter.Lanczos3);

ResizeFilter values, in order of quality/cost:

Filter	When to use
Nearest	Pixel art, speed-critical paths; fastest
Triangle	Quick downscale, acceptable quality
CatmullRom	Good general-purpose, moderate cost
Mitchell	Smooth downscale
Gaussian	Soft result, useful for thumbnails
Lanczos3	Highest-quality (default)

Thumbnail(maxWidth, maxHeight, filter)

Fit the image inside the bounding box while preserving aspect ratio. At most one dimension hits the bound; the other is smaller.

pipe.Thumbnail(400, 400);                // fits a 800×600 into 400×300
pipe.Thumbnail(400, 400, ResizeFilter.CatmullRom);   // faster than Lanczos3

If the source is already smaller than the bounds, Thumbnail is a no-op.

Crop(x, y, width, height)

Cut a rectangular region. Coordinates are in pixels from the top-left corner.

pipe.Crop(x: 100, y: 100, width: 400, height: 300);

Cropping past the image bounds throws ImagingException { Reason = InvalidArgument }.

Rotate(degrees)

Rotate by 90, 180, or 270 degrees (positive = clockwise). Arbitrary angles are not supported — the native layer only does lossless 90° rotations.

pipe.Rotate(90);    // landscape → portrait
pipe.Rotate(270);   // equivalent to Rotate(-90)

Passing any other value throws.

FlipHorizontal() / FlipVertical()

Mirror the image along the corresponding axis.

pipe.FlipHorizontal();   // left-right mirror
pipe.FlipVertical();     // top-bottom mirror

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Filters

Grayscale()

Convert to luminance-preserving grayscale. The pixel format remains RGB / RGBA — pixels just have equal R=G=B channels.

pipe.Grayscale();

Blur(sigma)

Gaussian blur. sigma is the standard deviation in pixels; sigma=1.0 is a light blur, 5.0 is heavy.

pipe.Blur(sigma: 2.0f);

Sharpen(sigma, threshold)

Unsharp-mask sharpening. sigma controls the radius of the underlying blur; threshold is the minimum pixel difference (0-255) that triggers sharpening.

pipe.Sharpen(sigma: 1.0f, threshold: 1);     // default
pipe.Sharpen(sigma: 1.5f, threshold: 3);     // stronger, ignores micro-noise

Low threshold sharpens everything (including noise); high threshold preserves smooth areas.

Brightness(value)

Add or subtract a constant to every RGB channel. Range -128 to +128.

pipe.Brightness(20);       // brighten
pipe.Brightness(-30);      // darken

Values outside the range are clamped native-side.

Contrast(value)

Multiplicative contrast. 1.0 is identity; >1.0 increases contrast; <1.0 flattens.

pipe.Contrast(1.2f);       // 20% more contrast
pipe.Contrast(0.8f);       // flatter

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Encoding

EncodeTo(stream, format, quality)

Serialise the current pipeline state to the stream. Quality ignored for PNG (lossless); applies to JPEG and WebP (0-100).

pipe.EncodeTo(output, ImageFormat.Png);
pipe.EncodeTo(output, ImageFormat.Jpeg, quality: 85);
pipe.EncodeTo(output, ImageFormat.Webp, quality: 80);

Supported output formats: PNG, JPEG, WebP, BMP.

After EncodeTo, the pipeline’s native buffer is released. Call Load again for a fresh pipeline.

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Inspection

ImageInfo.FromBytes(bytes) / FromStream(stream, maxBytes)

Parse the format header to read dimensions without a full decode. Returns:

public sealed record ImageInfo(
    ImageFormat Format,
    uint Width,
    uint Height);

Header-only parsing means this is cheap — use it to validate uploads before committing to a full ImagePipeline.Load.

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QR codes

QrCode.GeneratePng(text, output, moduleSize, margin)

Emit a PNG-encoded QR code directly to a stream.

Parameter	Default	Meaning
text	—	Payload — URL, text, any UTF-8 string
output	—	Target stream
moduleSize	10	Pixels per QR module
margin	2	Quiet-zone size in modules

Error correction level is fixed at Medium (automatic from qrcode crate defaults). For other levels or output formats, use a dedicated QR library.

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Combining operations

Typical transform chains:

// Thumbnail for a gallery
pipe.Thumbnail(400, 400, ResizeFilter.CatmullRom)
    .EncodeTo(out, ImageFormat.Webp, quality: 80);

// Sharpened grayscale scan
pipe.Resize(2048, 2048)
    .Grayscale()
    .Sharpen(sigma: 1.5f, threshold: 2)
    .EncodeTo(out, ImageFormat.Png);

// Rotate + crop + re-encode
pipe.Rotate(90)
    .Crop(x: 100, y: 200, width: 600, height: 400)
    .EncodeTo(out, ImageFormat.Jpeg, quality: 90);

Operations are applied in order. Ordering matters: Crop → Resize keeps the crop; Resize → Crop crops from the resized image.

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Bulk helpers

ImageConverter (in Pragmatic.Imaging) provides one-liner helpers that wrap the pipeline:

• ImageConverter.ThumbnailAsync(bytes, maxWidth, maxHeight, format, quality, options, ct)
• ImageConverter.ResizeAsync(bytes, width, height, format, quality, options, ct)
• ImageConverter.ConvertAsync(bytes, format, quality, options, ct)
• ImageConverter.StripMetadataAsync(bytes, format, quality, options, ct)

These are convenience wrappers — they open a pipeline, do the operation, encode, and return byte[].

ImageBatch wraps these for concurrent processing of multiple inputs.

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What’s not supported

• Arbitrary-angle rotation
• Text overlay / drawing
• Colour-space conversion (sRGB assumed throughout)
• Animation frames (GIF / APNG / animated WebP — first frame only)
• EXIF-preserving operations (EXIF is stripped on re-encode)
• Floating-point pixel formats
• HDR imagery

For any of the above, use ImageSharp or a dedicated tool.

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Related

• concepts.md — pipeline lifecycle, thread safety, memory model
• native-deployment.md — deploying the native binary