Images

Otty supports inline images via three protocols: iTerm2's OSC 1337, the Kitty graphics protocol, and Sixel.

images in bilibili-tui

iTerm2 protocol (OSC 1337)

Send a base64-encoded PNG / JPEG / GIF inline. Simplest usage:

imgcat ./icon.png         # imgcat ships with iTerm2 utilities; also works in Otty

Or manually:

printf '\e]1337;File=inline=1:%s\a' "$(base64 < ./icon.png)"

Supported parameters: inline, name, size, width, height, preserveAspectRatio.

Kitty graphics protocol

The richer of the two — supports placement at cursor, cell-based sizing, z-index, replacement, and deletion by ID.

kitty +kitten icat ./preview.png    # any Kitty-compatible viewer

What Otty implements today:

Feature	Status
Transmission: direct (t=d)	✓
Transmission: file (t=f / t=t)	✓
Transmission: chunked, zlib	✓
Transmission: shared memory (t=s)	planned
Formats: RGB, RGBA, PNG	✓
Placement (cursor, cell size, z-index, placement ID)	✓
Management (delete by id / placement / all, replace)	✓
Query / capability response (a=q)	✓
Unicode placeholders (U+10EEEE virtual placement)	✓
Animation (multi-frame, playback control)	planned
Relative placement (parent-child chains)	planned

Sixel

The classic DEC bitmap protocol, used by lsix, chafa -f sixel, img2sixel, gnuplot (set terminal sixel), mpv -vo sixel, and many neofetch-style tools. Otty advertises Sixel in its Device Attributes response, so tools that auto-detect terminal graphics (like chafa with no explicit format) pick it up automatically.

img2sixel ./photo.png       # ships with libsixel
chafa -f sixel ./photo.png  # chafa's sixel backend
lsix                        # thumbnail a directory of images

What Otty implements today:

Feature	Status
RGB and HLS color definitions	✓
Run-length encoding (!)	✓
Raster attributes (" — aspect + size)	✓
Transparent background (untouched pixels)	✓
Capability negotiation (DA1, XTSMGRAPHICS)	✓
VT340 default 256-color palette	✓

Images are placed at the cursor and the cursor advances below them, so sixel output scrolls into the scrollback like any other content.

Performance notes

• Images are uploaded once per ID and reused, even after clear.
• A small atlas caches recently-seen images; very large or rare images bypass.
• printf -based images larger than ~5 MB encoded should use chunked or file mode.

See also

• Unicode and Text Styles
• Notifications — OSC 9 / OSC 777.