SixLabors/ImageSharp · error · ArgumentException

Quality factor must be in [1..100] range.

Error message

Quality factor must be in [1..100] range.

What it means

JpegEncoder.Quality is an init-only property validated to be between 1 and 100 inclusive; values outside this range throw ArgumentException at construction/object-initializer time, before any encoding happens.

Solutions

1. Clamp the value before assigning: Math.Clamp(quality, 1, 100)
2. Validate user/config input range before constructing the encoder
3. Use ImageEncoderExtensions' quality-parameter overloads which document the 1-100 range
4. Fix scale conversion — e.g. some libraries use 0-100 where 0 must become 1

Example fix

// before
var encoder = new JpegEncoder { Quality = userQuality }; // ArgumentException if 0 or 101
// after
var encoder = new JpegEncoder { Quality = Math.Clamp(userQuality, 1, 100) };

if (quality is < 1 or > 100) throw new ArgumentOutOfRangeException(nameof(quality), "Quality must be in [1..100].");

static bool IsValidJpegQuality(int q) => q is >= 1 and <= 100;

When it happens

Trigger: new JpegEncoder { Quality = 0 } or Quality > 100 (or a negative value), typically computed from user input or an unclamped variable; also int values sourced from config or query strings.

Common situations: Mapping a UI slider or HTTP parameter straight into Quality; storing quality as a 0-99 scale from another library and passing it unclamped; off-by-one when '0 = lowest' is assumed.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• Progressive scans must be in [2..64] range.
• Restart interval must be in [0..65535] range.
• Could not find any converter for JpegColorSpace
• Invalid ICC profile.
• color

AI-assisted analysis of SixLabors/ImageSharp@59ce6af6fc (2026-09-13). Data as JSON: /api/errors/934c7b43965977ae. Report an issue: GitHub.

Appendix: source

Thrown at src/ImageSharp/Formats/Jpeg/JpegEncoder.cs:39

    /// <summary>
    /// Backing field for <see cref="RestartInterval"/>
    /// </summary>
    private int restartInterval;

    /// <summary>
    /// Gets the quality, that will be used to encode the image. Quality
    /// index must be between 1 and 100 (compression from max to min).
    /// Defaults to <value>75</value>.
    /// </summary>
    /// <exception cref="ArgumentException">Quality factor must be in [1..100] range.</exception>
    public int? Quality
    {
        get => this.quality;
        init
        {
            if (value is < 1 or > 100)
            {
                throw new ArgumentException("Quality factor must be in [1..100] range.");
            }

            this.quality = value;
        }
    }

    /// <summary>
    /// Gets a value indicating whether progressive encoding is used.
    /// </summary>
    public bool Progressive { get; init; }

    /// <summary>
    /// Gets number of scans per component for progressive encoding.
    /// Defaults to <value>4</value>.
    /// </summary>
    /// <remarks>
    /// Number of scans must be between 2 and 64.
    /// There is at least one scan for the DC coefficients and one for the remaining 63 AC coefficients.

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