Based on the search term bmp to jc5 converter work, it sounds like you are looking for a solution to convert standard image files (.bmp) into a proprietary or specific game asset format (.jc5).
Here is a breakdown of what you need to know to get this conversion working.
1. Understanding the Source: The BMP Architecture
To build a converter, one must first understand the source material. The BMP format is structurally simple but contains nuances that affect conversion.
Step 2: Decompression and Re-orientation
If the input BMP is 24-bit, the converter allocates a new buffer for the JC5 data.
- De-padding: The converter reads exactly $W \times (BPP/8)$ bytes per row, skipping the BMP padding.
- Vertical Flip: The converter writes the rows into the new buffer in reverse order. The first row read from the BMP becomes the last row in the memory buffer, resulting in a top-down orientation.
Step 1: BMP Parsing and Validation
The converter first reads the BMP file structure:
- Extracts the BITMAPFILEHEADER (signature "BM", file size, pixel offset).
- Reads the BITMAPINFOHEADER (width, height, bit depth, compression method).
Critical checks:
- Bit depth must be compatible (usually 1, 4, or 8 bits per pixel). True-color (24-bit) BMPs must be quantized down.
- Compression must be BI_RGB (uncompressed) or BI_RLE4/BI_RLE8. BI_JPEG or BI_PNG in BMP is not allowed.
If the BMP is incompatible, the converter returns an error or applies automatic downsampling.