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In this paper, a robust hash technique for image content authentication using histogram is proposed. The histogram based hash techniques reported in the literature are robust against Content Preserving Manipulations as well as incidental distortion. The major drawback of these techniques is that, they are not sensitive to Content Changing Manipulations and also un-altered histogram image modifications. To overcome these drawbacks, we present a novel hash technique which divides the image into non-overlapped blocks and distributes histogram bins of the image block into larger containers based on the Partial Sum of pixel count of histogram bins. An intermediate hash is produced by computing the ratio of pixel count between two neighbouring containers. The intermediate image hash is obtained by concatenating intermediate hashes of image blocks. Finally, the intermediate image hash is normalized and randomly permuted with a secret key to produce a robust and secure hash. The results shows that, the proposed method performs better when compared to the existing methods against the Content Preserving manipulations. Besides, the proposed method is more sensitive to Content Changing manipulations as well as un-altered histogram image modifications. The performance results on image authentication indicate that, the proposed method has high discriminative capability and strong robustness.

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