S·S SSI / Research article
NEURIPS 2026 · INTERACTIVE RESEARCH ARTICLE

Spectral-Spatial
Interpretation

Which spectral channels matter, and where?

SSI attributes a model score to individual spatial cells and input channels. It keeps the surrounding image observed while measuring how channels within one cell contribute to the selected prediction.

Haotian Ma · Ruqi Yang · Philip Townsend
Paper Figure 1 showing Painted Bunting RGB colors and Sentinel-2 multispectral evidence in water, vegetation and built-up areas
Figure 1 from the manuscript. Spatially different regions provide different spectral evidence; this motivating illustration is not an SSI numerical attribution result.
01 / THE QUESTION

Not just where.
Not just which channel.

A spatial map identifies relevant locations. A channel ranking summarizes relevance across an image. Neither alone tells us whether the same channel matters differently at different positions.

EXPLORE THE MOTIVATING EXAMPLES
Painted Bunting bird from paper Figure 1
Natural RGB image · paper Figure 1
SELECT A CHANNEL
Channel-specific illustration from paper Figure 1

Figure 1 uses visual / physical motivation. Real model-produced SSI scores are in the Playground below.
Spatial
×
Spectral
→One attribution for each cell and channel

Rather than enforce a rank-one product of one spatial map and one spectral vector, SSI retains a joint matrix of cell-by-channel contributions. Those contributions can be positive or negative.

02 / THE METHOD

Keep the context.
Explain one cell.

For a selected spatial cell, SSI measures the effect of its channels while the entire external image remains observed. Shapley values allocate that cell's masking contrast among its channels.

Paper method Figure 2 showing spatial grid, spectral channels, local Shapley game, joint attribution matrix and spatial/spectral summaries
Paper Figure 2. SSI performs channel attribution within each spatial cell, then aggregates the resulting joint matrix.
INTERACTIVE METHOD EXPLORERSchematic cell/channel selection · no invented model scores
SELECT A CELL

The highlighted cell is the only cell whose channels may be masked; all others remain observed.

SELECT A CHANNEL
CURRENT SELECTION
Cell 6 · SWIR1

Evaluate the chosen channel's marginal contribution across channel coalitions within this cell.

wg(R) = f(xBg ∪ R) − f(xBg)
01

Fix a target

Choose a class logit, or a fixed annotated region for segmentation. The target must not change when inputs are masked.

02

Keep other cells observed

Only channels in cell g are changed. Masked values use a specified per-channel baseline.

03

Allocate within g

Use ordinary Shapley values over the local channel game. Sum by cell or channel for two marginal summaries.

LOCAL EFFICIENCY
∑c Φ(g,c) = f(x) − f(xBg)

Exactly true for the local Shapley game (up to numerical or permutation-sampling error). It does not imply global input-to-baseline completeness after summing across cells.

The observed-context construction differs from MC-Owen attribution, which averages over external spatial coalitions. Read the paper for formal definitions and experimental assumptions.

03 / EXPLORE SSI

From model output
to a spatial-spectral explanation.

This is an actual repository example. The preview is a stored high-resolution research figure. Use the live Playground to recompute SSI from the original six-band tensor and verified ONNX checkpoint.

Real published SSI Visual Atlas figure for HLS Burn Scars sample 0163PUBLISHED ATLAS FIGURE · NOT A LIVE RUN
HLS BURN SCARS · SAMPLE 0163

Look at the spatial evidence, then the bands.

The fixed target is the annotated burn region. A signed spatial map is the sum over all six channels; per-channel overlays and the spectral summary preserve channel identities.

Blue · Green · Red · NIR · SWIR1 · SWIR2

Primary preview loads directly from the SSI repository; if unavailable, the image switches to labeled paper Figure 4, not a replacement sample result.

Compute this example ↗

Run real SSI in the browser

No simulated model inference is used by this article. The compute runtime lives in the maintained SSI Playground, where original inputs, models, settings and provenance are verified.

Open separately ↗
04 / PAPER EVIDENCE

Compare explanations
under the paper's tests.

Results below are transcribed from the NeurIPS paper, not produced by this web page. Error bars show reported bootstrap standard deviations, not confidence intervals or significance tests.

SOURCE · Table 1 · Same player space for each compared method · Mean ± bootstrap standard deviation

Spatial localization

Mean intersection-over-union of top-ranked spatial cells with the dataset's spatial annotation proxy.

TABLES 8–9 · mIoU ↑

Spectral ranking

Hit@K measures recovery of a predefined class-specific positive-prior band set; it is not pixel-level attribution ground truth.

TABLES 10–11 · Hit@K ↑
OBSERVED CONTEXT VS MC-OWEN

Fewer model evaluations in the paper's comparison.

The reported evaluation counts were up to 4,480 for SSI and 76,800 for MC-Owen. These are forward-pass counts, not wall-clock speed measurements.

5.8%

SSI evaluations relative to MC-Owen

Paper Figure 4 qualitative SSI comparisons with IG, DeepSHAP and KernelSHAP across RGB and multispectral data
Qualitative paper comparisons. These illustrative examples complement, but do not replace, the numerical masking, localization and channel-ranking evaluations.
Browse all results, settings and supplementary tables ↗
05 / VISUAL ATLAS

One method.
Fifty-seven examples.

Browse the complete released gallery across six model families. CUB-200, EuroSAT and HLS are in the paper's main benchmarks; PaviaU, Salinas and WHU-Hi-LongKou are additional interactive examples.

06 / REPRODUCE

Use SSI on your model.

The core public API accepts a model, a model-ready multichannel tensor, a fixed target, and a numerical per-channel baseline.

PYTHON · CORE API
from ssi import SSI

result = SSI(
    model=my_model,
    input=my_image,                # model-ready CHW tensor
    target=6,                      # fixed output class
    baseline=dataset_channel_mean,# one numeric value per channel
    image_size=(128, 128),
    grid_size=16,                  # cell extent in pixels -> 8x8 cells
    permutations=5,
).explain()

spatial, spectral = result.spatial, result.spectral

API grid_size refers to cell extent in pixels. The paper's 8×8 or 16×16 grid refers to the number of cells along each axis. Segmentation requires a fixed target region; a displayed RGB preview cannot replace the original multispectral input tensor.

07 / SCOPE & CITATION

What an SSI explanation means.

Observed context

External cells remain observed. SSI's within-cell allocation does not claim global completeness across interacting spatial locations.

Signed, model-dependent

Attributions depend on the model, target definition and specified masking baseline. Negative contributions are meaningful.

High-dimensional inputs

More bands increase the cost of local coalition evaluation; grouping and selective evaluation can be useful future directions.

Reference

Haotian Ma, Ruqi Yang, and Philip Townsend. Spectral-Spatial Interpretation. NeurIPS 2026. arXiv:2610.21114.

Credits & provenance

Figures and numerical results reflect the SSI paper and public repository. HLS derived data retain CC-BY-4.0 attribution. Other paper figures, weights and third-party source code may have distinct licenses.

Third-party notices ↗