Bristle Bitmap Corrector

Starting with the February 2024 update, Paint Tool SAI 2 implemented new security measures for brush textures. Some older brush files may be rejected and require correction using the Bristle Bitmap Corrector tool.

Important

If your custom brushes stopped working after updating SAI 2, this guide will help you fix them.

Background

What Changed

In February 2024, SYSTEMAX implemented stricter validation for brush texture files to:

  • Prevent potential security vulnerabilities

  • Ensure consistent brush behavior

  • Improve application stability

Affected Files

The following brush components may be affected:

  • Blotmap files - Brush shape textures

  • Brushtex files - Brush pattern textures

  • Elemap files - Element maps for special brushes

  • Scatter files - Particle scatter data

Symptoms of Invalid Textures

You may experience the following issues:

  • Brushes display as solid circles instead of textured

  • Error messages about invalid bitmap format

  • Brushes disappear from the brush list

  • Warning dialogs on startup about rejected files

Identifying Problem Files

Check the Log

  1. Launch SAI 2

  2. Look for warning messages on startup

  3. Check the application log (if available)

Manual Inspection

Invalid files often have:

  • Incorrect color depth (not 8-bit grayscale)

  • Wrong file dimensions

  • Corrupted file headers

  • Unsupported compression

Using the Bristle Bitmap Corrector

SAI 2 includes a built-in tool to correct invalid textures:

Step 1: Locate the Tool

The corrector tool is included in your SAI 2 installation:

  1. Navigate to your SAI 2 folder

  2. Look for saicorrt.exe or similar utility

  3. If not present, download from the SYSTEMAX website

Step 2: Backup Your Brushes

Warning

Always backup before making changes!

  1. Copy the following folders to a safe location:

    • blotmap/

    • brushtex/

    • elemap/

    • scatter/

Step 3: Run the Corrector

  1. Close SAI 2 completely

  2. Run the corrector tool

  3. Point it to your SAI 2 installation folder

  4. The tool will scan and identify invalid files

Step 4: Apply Corrections

The corrector tool will:

  • Convert invalid color depths to proper 8-bit grayscale

  • Fix file headers

  • Re-encode compressed files

  • Report unfixable files

Step 5: Verify

  1. Launch SAI 2

  2. Check that previously broken brushes now work

  3. Test brush functionality

Manual Correction Methods

If the automatic corrector doesn’t work, you can manually fix textures:

Using Image Editors

  1. Open the texture file in an image editor (Photoshop, GIMP, etc.)

  2. Convert to 8-bit Grayscale mode

  3. Save as BMP with no compression

  4. Replace the original file

Requirements for Valid Textures

  • Color Mode: 8-bit Grayscale

  • Format: Uncompressed BMP

  • Dimensions: Power of 2 recommended (256x256, 512x512, etc.)

  • Bit Depth: 8 bits per pixel

Using GIMP (Free)

  1. Open texture file in GIMP

  2. Image → Mode → Grayscale

  3. Image → Mode → 8 bpc

  4. File → Export As → BMP

  5. In export options: Select no compression, 8-bit

Creating Compatible Brush Textures

If you’re creating new brush textures:

Specifications

  • Size: 64x64 to 1024x1024 pixels (power of 2)

  • Color: Grayscale only

  • Depth: 8-bit

  • Format: BMP (uncompressed)

Design Tips

  • White = full opacity/effect

  • Black = no opacity/effect

  • Grays = partial effect

  • Consider tiling for pattern brushes

Common Issues and Solutions

“Bitmap format not supported”

Cause: Wrong color depth or compression

Fix: Re-save as 8-bit grayscale uncompressed BMP

“Texture dimensions invalid”

Cause: Non-standard dimensions

Fix: Resize to power of 2 (256, 512, 1024, etc.)

“File corrupted”

Cause: Damaged file or incomplete download

Fix: Re-download or restore from backup

Brushes still not working after correction

Try:

  1. Clear SAI 2 cache (delete temp files)

  2. Restart the application

  3. Reinstall the brush pack

  4. Check for updates to SAI 2

Prevention

To avoid issues in the future:

  1. Keep backups of working brush configurations

  2. Update SAI 2 regularly

  3. Download brushes from trusted sources

  4. Verify brush packs before installing

Trusted Brush Sources

  • Official SYSTEMAX brushes

  • Well-known artist brush packs

  • Brushes tested with current SAI versions

See Also