Example: Multi-page TIFF Round Trip

This example constructs a deterministic 5 × 64 × 64 volume. Slice intensity and a diagonal marker both vary with z, so reversing or duplicating IFD pages would change visible data and fail the exact voxel comparison. The source uses non-default medical geometry to exercise the separate metadata contract.

The first two panels intentionally use the same display range. They should look identical. The third panel is the decisive comparison: blue means every displayed voxel is bit-identical, red would mark any mismatch, and the numeric maximum must remain zero. The final panel is expected to differ because the current TIFF writer and reader do not carry RITK’s full physical geometry.

Public API

use coeus_core::SequentialBackend;
use ritk_tiff::{read_tiff, write_tiff};

let backend = SequentialBackend;
write_tiff(&source, "stack.tiff", &backend)?;
let decoded = read_tiff("stack.tiff", &backend)?;

The decoded shape is [number_of_IFDs, rows, columns]. In this example:

page 1 → z = 0
page 3 → z = 2
page 5 → z = 4

The program compares f32::to_bits() at every voxel before writing the figure. A page-order, value, or shape defect therefore stops the example instead of producing a plausible image.

Geometry restoration is explicit

The source uses origin [10, -20, 30] mm, spacing [0.5, 0.75, 2] mm, and a 90-degree axial rotation. The decoded TIFF correctly has zero origin, unit spacing, and identity direction under the current API contract. Applications must replace those defaults from a trusted source before physical resampling or registration.

Run it

From the repository root:

cargo run -p ritk-tiff --example book_tiff -- \
  docs/book/figures/tiff_roundtrip.svg

The TIFF itself is temporary. Only the deterministic SVG is retained. The complete runnable source is crates/ritk-tiff/examples/book_tiff.rs.