Batch Image Converter for OziExplorer: Save Time on Map PrepPreparing maps for use in OziExplorer can be time-consuming if you’re working with many images, varying formats, or inconsistent resolutions. A batch image converter automates repetitive steps — format conversion, resizing, color adjustment, and georeferencing prep — letting you focus on mapping rather than manual file handling. This article walks through why batch conversion matters, what features to look for, a recommended workflow, tool options, and practical tips to speed up your map preparation.
Why batch conversion matters for OziExplorer users
OziExplorer accepts several map image formats (BMP, JPG, PNG, TIF) and benefits from consistent image characteristics across tiles or map sheets. Converting images one by one is slow and error-prone. Batch conversion:
- Reduces manual work when dealing with dozens or hundreds of map tiles.
- Ensures consistent resolution, color profile, and file format across all map images.
- Prepares images for georeferencing by applying the same resize/crop operations.
- Enables automated generation of OziExplorer-compatible files (like converting to BMP and creating associated world files).
Time saved scales with the number of images — batch processing that takes minutes for hundreds of files replaces hours of repetitive manual edits.
Key features to look for in a batch image converter
Choose a tool that offers the following capabilities to streamline OziExplorer map prep:
- Support for common map image formats: BMP, JPG, PNG, TIFF, and GeoTIFF.
- Batch format conversion (e.g., PNG → BMP).
- Batch resizing and resampling with control over DPI and interpolation method.
- Color adjustments (brightness/contrast, gamma, color profile conversion) and dithering options.
- Cropping and padding to make tiles uniform in pixel dimensions.
- Preservation or handling of transparency (important for overlay maps).
- Ability to write or export world files (.map or .wld) or integration with georeferencing tools.
- Command-line interface or scripting support for automation.
- Error handling, logging, and a preview option for sample images.
Recommended workflow for preparing map images for OziExplorer
-
Inventory and backup
- Gather all source images in a single directory. Make a backup copy before batch operations.
-
Standardize format
- Convert all images to the preferred format for OziExplorer (BMP often recommended for older Ozi versions, but JPG/PNG/TIF work depending on your needs).
-
Normalize size and resolution
- Resize images to uniform pixel dimensions and set a consistent DPI (dots per inch). Use an appropriate resampling method (Lanczos for best quality, bilinear for speed).
-
Adjust color and contrast
- Apply consistent color correction, gamma, or histogram equalization so tiles match visually.
-
Handle transparency and overlays
- For overlay maps, preserve alpha channels (PNG) and ensure transparent areas are correctly handled by OziExplorer.
-
Generate or prepare georeference files
- If you have geospatial metadata (GeoTIFF), export world file(s) or convert metadata into OziExplorer map files. If not, batch conversion should prepare images for subsequent georeferencing steps.
-
Validate
- Open a representative sample of converted maps in OziExplorer to confirm alignment, color, and metadata.
Tools and options
Below are several approaches depending on your comfort level and needs.
-
GUI batch converters (easy, visual)
- XnConvert / XnView MP — broad format support, batch processing, filters, scripting. Good for non-technical users.
- IrfanView (with plugins) — fast, lightweight batch conversion and basic image operations.
- Photoshop / GIMP with macros — powerful but heavier; use actions or scripts for batch tasks.
-
Command-line & scripting (powerful, automatable)
- ImageMagick — extremely flexible for format conversion, resizing, color changes, and metadata handling. Example:
magick mogrify -format bmp -resize 4096x4096 -quality 92 *.png
- GDAL (gdal_translate, gdalwarp) — the standard for geospatial raster processing, especially for GeoTIFFs and coordinate transforms. Example:
gdal_translate -of AAIGrid input.tif output.asc gdalwarp -t_srs EPSG:4326 input.tif output_wgs84.tif
- Python (Pillow + rasterio) — build custom pipelines for mixed tasks, like batch converting and generating OziExplorer .map files.
- ImageMagick — extremely flexible for format conversion, resizing, color changes, and metadata handling. Example:
-
Specialized map-prep utilities
- MapTiler / MapTiler Desktop — creates tiles and can export in formats compatible with various viewers; useful if you need web tiles or consistent tiling schemes.
- Global Mapper — commercial GIS tool with strong raster handling and export options.
Example: Batch prepare PNG tiles for OziExplorer using ImageMagick
Steps (concise):
- Convert PNG to BMP (if needed), resize to a uniform size, and adjust color:
magick mogrify -format bmp -resize 4096x4096 -colorspace sRGB -quality 95 *.png
- If you need to preserve transparency and keep PNG:
magick mogrify -resize 4096x4096 -colorspace sRGB *.png
For tiles with embedded geo-information, use GDAL to extract or reproject metadata before conversion:
gdalwarp -t_srs EPSG:4326 input_geotiff.tif output_wgs84.tif gdal_translate -of GTiff output_wgs84.tif cleaned_output.tif
Generating OziExplorer .map files in batch
OziExplorer uses .map files to store georeference control points and projection settings. You can automate .map creation by scripting templates populated with known control points or metadata extracted via GDAL/rasterio. A typical .map file includes image filename, map projection, datum, and coordinate pairs for at least three control points. If your source images have embedded georeferencing (GeoTIFF), extract corner coordinates and write .map files programmatically.
Practical tips & pitfalls
- Test on a small subset before batch-processing everything.
- Keep originals — reversible workflows save headaches.
- Beware of lossy formats (JPEG) if fine detail is critical; use TIFF or PNG where possible.
- Pay attention to color profiles — inconsistent profiles lead to visible seams when tiles are joined. Convert all images to sRGB or your target profile.
- When creating tiles, ensure overlap and edge consistency to avoid visible seams in OziExplorer.
- If you depend on control points, automate extraction from GeoTIFF tags with GDAL or rasterio to avoid manual transcription errors.
Conclusion
A good batch image converter is a multiplier for efficiency when preparing maps for OziExplorer. Choose tools that support the formats, geospatial metadata, and automation level you need; test settings on samples; and script repetitive steps to eliminate manual errors. With the right pipeline, hundreds of map sheets can be standardized and made OziExplorer-ready in minutes rather than days.