SIX to HEIC Converter

Convert terminal imagery to compact HEIC format online

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Simple Workflow

Upload SIX, pick HEIC, download the result — the three-step process makes converting legacy formats effortless for anyone.

Server-Side Speed

Heavy lifting happens in the cloud — your device resources are untouched while SIX images are processed into HEIC format.

No Install Required

The entire SIX to HEIC conversion runs in your browser. No desktop software, no plugins — just upload and convert.

How to convert SIX to HEIC

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose heic or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your heic file right afterwards

About formats

SIX is a file extension for SIXEL (Six Pixel) graphics data, a bitmap graphics format developed by Digital Equipment Corporation (DEC) in 1983 and introduced with the LA50 dot matrix printer. SIXEL encodes images as a sequence of printable ASCII characters, where each character represents a column of six vertical pixels (a 'sixel') — the character's ASCII value minus 63 provides a 6-bit binary pattern, with each bit controlling one pixel in the vertical column. The encoding is structured as a series of sixel bands (each six pixels tall) across the image width, with control sequences for color selection (up to 256 registers with HLS or RGB specification), repeat counts (run-length encoding for efficiency), carriage return, and newline commands. SIXEL data is transmitted to the output device using DEC's standard escape sequence protocol, embedded within the text stream alongside regular character output. Originally designed for DEC's line of printers and later supported by DEC VT-series terminals (VT240, VT330, VT340), SIXEL has experienced a remarkable revival in modern terminal emulator software. One advantage is terminal-native image display: SIXEL allows images to be rendered directly within a text terminal session without requiring a graphical window system, enabling command-line tools to display graphs, photographs, and previews inline with text output. This capability has driven adoption in modern terminals like mlterm, xterm, WezTerm, and foot. SIX/SIXEL data can be generated by ImageMagick, libsixel, and chafa, and viewed in any SIXEL-capable terminal emulator.
Initial release: 1983
HEIC (High Efficiency Image Container) is Apple's branded implementation of the HEIF (High Efficiency Image File Format) standard that uses HEVC (H.265) as its image compression codec. Apple adopted HEIC as the default photo format on iPhones and iPads starting with iOS 11 in September 2017, replacing JPEG for newly captured images. HEIC files store photographs compressed with the intra-frame coding mode of the HEVC video codec, which applies sophisticated prediction, transform, and entropy coding techniques that achieve roughly 50% better compression than JPEG at equivalent visual quality. The ISOBMFF (ISO Base Media File Format) container supports multiple images in a single file, enabling Live Photos (a still plus a short video clip), burst sequences, depth maps from dual-camera systems, and HDR gain maps that allow compatible displays to render extended dynamic range. HEIC also stores alpha channels, auxiliary images for computational photography features (portrait mode depth data, semantic segmentation masks), and comprehensive EXIF/XMP metadata. One advantage is storage efficiency: iPhones shooting HEIC use roughly half the storage of equivalent JPEG captures with no visible quality loss, a significant benefit on devices where storage is finite and photos accumulate rapidly. The format's integration with Apple's ecosystem is another key strength — HEIC files are natively supported across macOS, iOS, iPadOS, and iCloud Photos, and automatic JPEG transcoding during file sharing ensures compatibility when sending photos to non-Apple devices. HEIC can also be opened by Windows 10/11 (with codec), GIMP, ImageMagick, and Adobe Lightroom.
Developer: MPEG / Apple
Initial release: 2015

Frequently Asked Questions

Why convert SIX to HEIC?

SIX encodes images as text for DEC terminals — useless outside that environment. Converting to HEIC yields a standard image you can use anywhere.

What programs can open HEIC?

Apple devices open HEIC natively. Windows 10+ supports it via an extension. Photoshop, GIMP, and IrfanView handle HEIC as well.

Will I lose image quality converting SIX to HEIC?

Some compression artifacts are possible since HEIC is a lossy format. Choosing maximum quality preserves visual fidelity as closely as possible.

Is SIX to HEIC conversion fast?

The process is fast — cloud-based processing handles SIX to HEIC conversion in seconds for standard-sized images, even on slower connections.

Can I convert multiple SIX images at once?

Yes — upload multiple SIX files in one session and convert them all to HEIC simultaneously. Batch processing saves time on repetitive tasks.