Tonal Dither

Give shadows and highlights their own texture

Tonal Dither converts PNG images into a chosen palette, with separate dither-strength controls for dark and light areas. Add more pattern to shadows while keeping highlights quieter, then adjust where the two settings meet. Both settings are applied in one conversion, without separately exporting and combining two versions.

Features

• Separate Shadows and Highlights controls, with adjustable Crossover and Blend width
• Built-in grayscale and RGB palettes, plus custom palettes of 2–32 unique HEX colors
• Source/result comparison and PNG export at the original pixel dimensions
• Save and load settings as JSON presets
• Process up to 10 PNGs using one shared set of settings
• Export one PNG or a ZIP with a processing report and unique filenames
• English and Japanese interface

How to use it

Download and extract the ZIP, then open index.html in a compatible desktop browser. Choose Texture sample for a first test, or Add PNG images for your own files. Adjust the palette and tonal strengths, then choose Download PNG or Export all as ZIP.

The self-contained HTML tool processes images locally in your browser. It has no image-upload, account or tracking feature and never overwrites your source files. Save your presets and outputs before closing the page; the queue and unsaved settings are not retained.

Important limits and color handling

• PNG only: static, non-interlaced 8/16-bit RGB, RGBA, grayscale and grayscale+alpha, plus 1/2/4/8-bit indexed or grayscale PNG. JPEG, animated PNG and interlaced PNG are unsupported
• Every export is an untagged 8-bit RGBA PNG. 16-bit input is rounded to 8-bit before processing, including alpha, reducing color and transparency precision
• 8-bit alpha is preserved. Embedded color profiles, gamma adjustments and orientation metadata are not applied; metadata is removed on export. Use an sRGB PNG with its orientation already applied to the pixels
• A strength of 0 still converts colors to the selected palette. Coarse palettes and material presets can shift hues substantially
• Maximum 25 MiB per input/output PNG, 4096 pixels per side and 8,388,608 pixels per image. Up to 10 files, 64 MiB combined input and 64 MiB ZIP contents. Processing and export limits may be reached sooner on some devices
• Batch settings are shared. There are no per-image recipes or brush masks

Compatibility

Requires a desktop browser with Web Workers and CompressionStream/DecompressionStream. Selected workflows and downloads were checked in Chrome 154 and Safari 27 on macOS over HTTP. Basic direct-file opening and sample PNG export were also manually confirmed on a Mac. This is not a complete offline browser test matrix. Windows, Firefox and mobile are unverified.

AI disclosure

The software and written materials were developed with generative-AI assistance. Image processing uses fixed local algorithms and does not call an AI service.

Support: s41-support@agentmail.to

日本語

Tonal Ditherは、暗部と明部のディザの強さを別々に調整できるPNG変換ツールです。境界位置と混ぜる幅、2〜32色のカスタムパレット、設定の保存・読み込み、最大10枚の一括ZIP書き出しに対応。画面は日本語・英語を切り替えられます。

ZIPを展開してindex.htmlを開き、「質感サンプル」で試すか、「PNG画像を追加」で読み込みます。調整後は「PNGをダウンロード」または「全画像をZIPで書き出す」を選びます。画像はブラウザー内で処理し、元ファイルは変更しません。

重要：出力はすべて8-bit RGBA PNGです。16-bit入力は透明度も含めて8-bitに丸めるため、精度が低下します。ICCプロファイル、ガンマ補正、Exifの向きは反映せず、メタデータも残しません。強さ0でも減色は行い、設定は全画像で共通です。JPEG・アニメーションPNG・インターレースPNGは非対応です。

上限は各PNG 25 MiB、各辺4096 px、1枚8,388,608画素、最大10枚、入力合計64 MiB、ZIP内容合計64 MiBです。macOSのChrome 154・Safari 27で一部操作を確認し、Macでの直接起動とサンプルPNG保存も確認済みです。Windows・Firefox・モバイルは未確認です。ソフトウェアと文章の制作には生成AIを使用しています。

Support: s41-support@agentmail.to

License

For use by the purchaser only, for personal and commercial projects. You may sell exported images provided you have the necessary rights to the source material. Redistribution or resale of the tool itself is prohibited.

利用条件

購入者本人による個人・商用利用が可能です。出力画像は、元の素材について必要な権利を持つ範囲で販売できます。ツール本体の再配布・転売は禁止します。