Jovian Logic VI
Jovian Logic VI (or Jovian VI) is a raster image format associated with Jovian Logic video capture boards (maybe the "VIA" models in particular?). It is difficult to find any authoritative information about it.
It appears to be a relatively simple uncompressed format, with a 16-byte header. It supports truecolor, grayscale, and paletted images.
Identification
Files apparently begin with the ASCII signature "VI".
Format details
This information is based on reverse engineering and guesswork. It may not be correct.
Multi-byte integers are little-endian. Offsets are in bytes, from the beginning of the file.
| Offset | Length | Field | Details |
|---|---|---|---|
| 0 | 2 | signature | Always 0x56 0x49 (ASCII "VI") |
| 2 | 1 | image_type |
0x10 = RGB, 16 bits/pixel (R5-G6-B5) |
| 3 | 2 | width | Image width in pixels |
| 5 | 2 | height | Image height in pixels |
| 7 | 2 | ? | Unknown purpose. Can be 0. |
| 9 | 1 | pal_code |
0 = Palette entries have 6 bits/sample (18-bit color) |
| 10 | 1 | pal_first_index | Index of the first palette entry stored in the file (typically 0) |
| 11 | 1 | pal_length | Number of palette entries stored in the file. 0 means 256. |
| 12 | 2 | pal_offset | Offset of the palette data |
| 14 | 2 | image_offset | Offset of the image data |
| pal_offset | pal_length×3 | palette_data | Only present for paletted images. |
| image_offset | image_data | Pixels are in left-to-right, top-to-bottom order. Rows are padded to the next byte boundary. |
