Understanding Gene Expression-to-Image Learning: Spatial Structure and Information Fidelity
Organizations: College of Computer Science and Electronic Engineering, Hunan University, Changsha, China · University of Electronic Science and Technology of China, Chengdu, China · Xiamen University, Xiamen, China · State Key Laboratory of Chemo and Biosensing, Institute of AI4Science, Hunan University, Changsha 410082, P. R. China ·
Abstract
Single-cell RNA sequencing (scRNA-seq) enables cell-level analysis of biological heterogeneity, but learning effective representations from high-dimensional, unordered gene expression profiles remains challenging. Gene Expression-to-Image (GE2I) offers an effective learning strategy by arranging gene values on pixel grids for convolutional neural networks, but its underlying mechanisms remain unclear. We study GE2I on full-transcriptome data while keeping the network and training procedure fixed. Our results reveal a trade-off between spatial smoothness and gene-level fidelity. Structured mappings produce smooth, low-frequency patterns that support faster early optimization, whereas assigning multiple genes to the same pixel obscures expression differences and can reduce predictive performance. This trade-off explains why random mappings can compete with structured layouts when many genes are represented. One-to-one gene-to-pixel assignment improves prediction across the tested visual backbones even when image smoothness decreases. We further find that the benefits of pretraining and augmentation depend on the backbone and mapping. These findings provide practical guidance for pixel allocation and the transfer of vision priors to gene expression data.
Figures & tables
| DKD | GTEx v9 | HypoMap | Immune Cell Atlas | Tabula Sapiens | ||||||
| Method | ACC | F1-M | ACC | F1-M | ACC | F1-M | ACC | F1-M | ACC | F1-M |
| XGBoost | ||||||||||
| scANVI | ||||||||||
| scANVI (scArches) | ||||||||||
| Seurat | ||||||||||
| scGPT | - | - | ||||||||
| DKD | GTEx v9 | HypoMap | Immune Cell Atlas | Tabula Sapiens | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Method | Acc | F1-M | Acc | F1-M | Acc | F1-M | Acc | F1-M | Acc | F1-M |
| scGPT | - | - | ||||||||
| Random | ||||||||||
| DeepInsight (t-SNE) | ||||||||||
| DeepInsight (UMAP) | ||||||||||
| DeepInsight (PCA) | ||||||||||
| Target | Descriptor | Coef. | Cluster SE | |||
|---|---|---|---|---|---|---|
| Accuracy | APPG | -1.044 | 0.358 | -2.92 | 0.006 | 0.011 |
| CR | -3.251 | 0.617 | -5.27 | |||
| LFER | 4.954 | 1.367 | 3.62 | 0.003 | ||
| SE | 0.933 | 0.265 | 3.52 | 0.001 | 0.003 | |
| F1-Macro | APPG | -0.966 | 0.414 | -2.33 | 0.026 | 0.041 |
| CR | -3.349 | 0.791 | -4.23 | 0.001 |
| Dataset | Mapping | APPG | CR | LFER | SE | Acc | F1-M |
|---|---|---|---|---|---|---|---|
| DKD | DeepInsight (t-SNE) | 1.0000_{\pm 0.00}^{{\color[rgb]{0.8867,0.543,0.543}+104.8\%}} | 0.0000_{\pm 0.00}^{{\color[rgb]{0.418,0.6211,0.8594}-100.0\%}} | 0.8021_{\pm 0.00}^{{\color[rgb]{0.418,0.6211,0.8594}-15.0\%}} | 2.3435_{\pm 0.00}^{{\color[rgb]{0.8867,0.543,0.543}+19.7\%}} | 0.9679_{\pm 0.00}^{{\color[rgb]{0.8867,0.543,0.543}+1.5\%}} | 0.9047_{\pm 0.00}^{{\color[rgb]{0.8867,0.543,0.543}+2.0\%}} |
| DKD | DeepInsight (UMAP) | 1.0000_{\pm 0.00}^{{\color[rgb]{0.8867,0.543,0.543}+84.8\%}} | 0.0000_{\pm 0.00}^{{\color[rgb]{0.418,0.6211,0.8594}-100.0\%}} | 0.7811_{\pm 0.00}^{{\color[rgb]{0.418,0.6211,0.8594}-13.5\%}} | 2.4673_{\pm 0.00}^{{\color[rgb]{0.418,0.6211,0.8594}-10.0\%}} | 0.9667_{\pm 0.00}^{{\color[rgb]{0.8867,0.543,0.543}+1.0\%}} | 0.9006_{\pm 0.02}^{{\color[rgb]{0.8867,0.543,0.543}+0.9\%}} |
| GTEx v9 | DeepInsight (t-SNE) | 1.0000_{\pm 0.00}^{{\color[rgb]{0.8867,0.543,0.543}+142.0\%}} | 0.0000_{\pm 0.00}^{{\color[rgb]{0.418,0.6211,0.8594}-100.0\%}} | 0.7560_{\pm 0.04}^{{\color[rgb]{0.418,0.6211,0.8594}-12.8\%}} | 2.7173_{\pm 0.30}^{{\color[rgb]{0.8867,0.543,0.543}+2.8\%}} | 0.8630_{\pm 0.03}^{{\color[rgb]{0.8867,0.543,0.543}+1.0\%}} | 0.5557_{\pm 0.02}^{{\color[rgb]{0.8867,0.543,0.543}+9.7\%}} |
| GTEx v9 | DeepInsight (UMAP) | 1.0000_{\pm 0.00}^{{\color[rgb]{0.8867,0.543,0.543}+271.3\%}} | 0.0000_{\pm 0.00}^{{\color[rgb]{0.418,0.6211,0.8594}-100.0\%}} | 0.7374_{\pm 0.05}^{{\color[rgb]{0.418,0.6211,0.8594}-8.0\%}} | 2.8200_{\pm 0.32}^{{\color[rgb]{0.418,0.6211,0.8594}-12.0\%}} | 0.8495_{\pm 0.04}^{{\color[rgb]{0.8867,0.543,0.543}+0.4\%}} | 0.5357_{\pm 0.05}^{{\color[rgb]{0.8867,0.543,0.543}+9.7\%}} |
| HypoMap | DeepInsight (t-SNE) | 1.0000_{\pm 0.00}^{{\color[rgb]{0.8867,0.543,0.543}+229.2\%}} | 0.0000_{\pm 0.00}^{{\color[rgb]{0.418,0.6211,0.8594}-100.0\%}} | 0.8602_{\pm 0.00}^{{\color[rgb]{0.418,0.6211,0.8594}-9.4\%}} | 2.0356_{\pm 0.07}^{{\color[rgb]{0.418,0.6211,0.8594}-7.7\%}} | 0.9940_{\pm 0.00}^{{\color[rgb]{0.8867,0.543,0.543}+0.2\%}} | 0.7945_{\pm 0.13}^{{\color[rgb]{0.8867,0.543,0.543}+6.1\%}} |
| HypoMap | DeepInsight (UMAP) | 1.0000_{\pm 0.00}^{{\color[rgb]{0.8867,0.543,0.543}+359.5\%}} | 0.0000_{\pm 0.00}^{{\color[rgb]{0.418,0.6211,0.8594}-100.0\%}} | 0.8085_{\pm 0.05}^{{\color[rgb]{0.418,0.6211,0.8594}-11.7\%}} | 2.2516_{\pm 0.34}^{{\color[rgb]{0.418,0.6211,0.8594}-21.8\%}} | 0.9938_{\pm 0.00}^{{\color[rgb]{0.8867,0.543,0.543}+0.0\%}} | 0.8137_{\pm 0.13}^{{\color[rgb]{0.8867,0.543,0.543}+5.5\%}} |
Appendix figures & tables9 assets
Supplementary material from the paper’s appendix.
Appendix
| Dataset | Samples | Genes | Classes/Targets | Batches | Imbalance |
| Task 1: Cell Type Classification | |||||
| Diabetic Kidney Disease | 39,176 | 27,980 | 13 | 11 | 54.7 |
| GTEx v9 | 209,126 | 28,094 | 53 | 16 | 956.0 |
| Immune Cell Atlas | 329,762 | 29,335 | 35 | 12 | 964.4 |
| HypoMap | 384,925 | 41,642 | 13 | 24 | 5,350.2 |
| Tabula Sapiens | 483,152 | 55,904 | 160 | 29 | 11,734.7 |
| Method | RMSE | Overall PCC | Overall Spearman |
|---|---|---|---|
| Random Mapping | |||
| DeepInsight (t-SNE) | |||
| DeepInsight (UMAP) | |||
| DeepInsight (PCA) | |||
| MR-DeepInsight | |||
| Fotomics |
| Metric | DKD | GTEx v9 | HypoMap | ICA | TS |
|---|---|---|---|---|---|
| Acc | |||||
| F1-M |
| Method | Augmentation | ACC | F1-Macro |
|---|---|---|---|
| DeepInsight (t-SNE) | None | ||
| Geometric | |||
| Bio. Cutout | |||
| Bio. Noise | |||
| Bio. Intensity | |||
| All |
| Setting | Random | DeepInsight (t-SNE) | Key evidence |
|---|---|---|---|
| CAM entropy | 0.950 | 0.907 | more compact saliency |
| Center mass | 0.427 | 0.521 | stronger spatial focus |
| Marker hit ratio | 0.25 | 0.50 | better biological alignment |
| DCT marker coverage | 2/5 | 5/5 | SLC12A3, PVALB, TRPM6, CALB1, FXYD2 |
| TAL marker coverage | 2/5 | 4/5 | UMOD, SLC12A1, KCNJ1, CLDN16 |
| Podocyte marker coverage | 2/5 | 5/5 | NPHS1, NPHS2, PODXL, WT1, SYNPO |
| Method | Dataset | APPG | CR | LFER | SE | Acc | F1-M |
|---|---|---|---|---|---|---|---|
| Highly Variable Genes (HVG) | |||||||
| Random | DKD | 1.000 | 0.000 | 0.177 | 3.029 | 0.900 | 0.773 |
| Random | GTEx | 1.000 | 0.000 | 0.198 | 3.033 | 0.653 | 0.211 |
| Random | HypoMAP | 1.000 | 0.000 | 0.191 | 3.030 | 0.980 | 0.557 |
| Random | ICA | 1.000 | 0.000 | 0.207 | 3.034 | 0.683 | 0.484 |
| Random | Tabula Sapiens | 1.000 | 0.000 | 0.221 | 3.026 | 0.384 | 0.215 |
Single-Cell Transcriptomics
Single-cell transcriptomics measures gene activity cell by cell to map cell types, states, interactions, and responses across tissues and conditions.
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