Abstract: Integrity checking apparatus and procedures for checking safety-critical high throughput data and image transformations. The present invention randomly samples input and output data streams and uses the sampled data in either a forward or backward transformation to verify that the input data and output data are consistent. Because only a small fraction of the overall data is examined, the computational workload is very small by comparison, and processing may be more efficiently implemented. More particularly, in order to check the data, input data is transformed into output data, the output data is sampled, the input data is sampled corresponding to the sampled output data, and the input data is calculated from the output data, using forward or backward (inverse) data transformations. If the sampled input data and sampled output data correspond, then the output data is deemed to be correct. If the data does not correspond, then an error signal is generated.