Table of Contents

Color and Effects

Color adjustments are where many small ImageSharp processors start to feel composable instead of isolated. You can reach for named helpers like Grayscale() and Sepia(), or drop down to ColorMatrix when you want to express the transformation yourself.

ImageSharp includes a wide range of processors for tonal adjustment, color transforms, and simple stylistic effects. Common entry points include Grayscale(), Sepia(), Brightness(), Contrast(), Hue(), Saturate(), and Opacity(). Under the hood, many of these effects are expressed as a ColorMatrix and applied with Filter().

Convert to Grayscale

Use Grayscale() to remove color information:

using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Processing;

using Image image = Image.Load("input.jpg");

image.Mutate(x => x.Grayscale());

ImageSharp also supports GrayscaleMode when you need a specific conversion mode.

Grayscale conversion is not just averaging red, green, and blue. Different modes weight channels differently, and those choices affect perceived brightness. Use a specific GrayscaleMode when output must match a known visual or analytical expectation.

Apply a Sepia Tone

Use Sepia() for a classic warm-tone effect:

using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Processing;

using Image image = Image.Load("input.jpg");

image.Mutate(x => x.Sepia());

Adjust Brightness and Contrast

Use Brightness() and Contrast() to tune exposure and punch:

using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Processing;

using Image image = Image.Load("input.jpg");

image.Mutate(x => x
    .Brightness(1.1F)
    .Contrast(1.2F));

Values greater than 1 increase the effect. Values less than 1 reduce it.

Brightness and contrast are simple global operations. They are useful for quick output tuning, but they do not replace tone mapping, exposure recovery, or color-managed workflows. Apply them after geometry changes when the effect is meant for the final exported image.

Shift Hue and Saturation

Use Hue() and Saturate() when you want to push color balance or intensity:

using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Processing;

using Image image = Image.Load("input.jpg");

image.Mutate(x => x
    .Hue(30)
    .Saturate(1.25F));

Hue shifts rotate color relationships, while saturation changes color intensity. Both can create out-of-gamut or unnatural-looking results if pushed too far. Use small values for photographic correction and stronger values for intentional stylized output.

Adjust Opacity

Use Opacity() to reduce alpha values across the image:

using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Processing;

using Image image = Image.Load("input.png");

image.Mutate(x => x.Opacity(0.5F));

This is most useful when working with images that already include transparency.

Opacity changes alpha values; it does not composite the image onto a background. If the final format cannot store alpha, use BackgroundColor() or another compositing step before saving.

Use ColorMatrix for Custom Filters

ColorMatrix is the low-level type for custom channel transforms. It is a 5x4 matrix over the color and alpha channels, and Filter() applies that matrix to the image.

That makes ColorMatrix the right tool when the built-in processors are close to what you need but not quite exact. The diagonal fields such as M11, M22, M33, and M44 scale channels, while the last-row fields such as M51, M52, and M53 add channel bias.

using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Processing;

using Image image = Image.Load("input.jpg");

ColorMatrix warmTone = new()
{
    M11 = 1.08F,
    M22 = 1.00F,
    M33 = 0.92F,
    M44 = 1F,
    M51 = 0.02F
};

image.Mutate(x => x.Filter(warmTone));

Reuse Known Filter Matrices

If you want matrix-based control without building every matrix by hand, use KnownFilterMatrices. The built-in brightness, contrast, grayscale, hue, saturation, opacity, sepia, and preset camera-look filters all come from this API surface.

using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Processing;

using Image image = Image.Load("input.jpg");

ColorMatrix matrix =
    KnownFilterMatrices.CreateHueFilter(20F)
    * KnownFilterMatrices.CreateSaturateFilter(1.15F);

image.Mutate(x => x.Filter(matrix));

You can also use the predefined matrices directly for stylized looks such as KodachromeFilter and PolaroidFilter.

Chain Effects in a Single Pipeline

These processors are designed to compose cleanly:

using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Processing;

using Image image = Image.Load("input.jpg");

image.Mutate(x => x
    .AutoOrient()
    .Resize(800, 800)
    .Brightness(1.05F)
    .Contrast(1.1F)
    .Saturate(1.15F));

As with other processors, order matters when combining effects.

Practical Guidance

Apply color effects after geometry changes when the effect is output-specific. Keep source images in a suitable working color space before judging color adjustments, and use explicit encoder settings afterward so compression does not hide the result you tuned. Test effects on representative images, because a setting that flatters one sample can damage skin tones, brand colors, gradients, or shadows elsewhere.

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