## 6 Conclusions  
This paper proposes a computationally efficient and novel entropy and histogram retained \(MPSA\) RDH scheme. The majority of the existing RDH schemes modify the encrypted cover image pixels to hide the secret data, raising security concerns over the operated encryption algorithm. The entropy of the encrypted image and the histogram of the encrypted image are two useful parameters that quantify the encryption algorithm's efficiency. Our proposed \(MPSA\) scheme is completely reversible and is suitable for any encryption algorithm. The proposed data-hiding process does not change the encrypted cover image pixel intensities, maintaining the same entropy and the same histogram of the encrypted cover image. Thus, the encryption efficiency of the encryption algorithm is not compromised. Moreover, the data-embedding process is independent of the structure or any statistical measures of the cover image, achieving a constant embedding rate on all images. The proposed \(MPSA\) allows an embedding of 0.03125 bits per pixel for most of the USC-SIPI images and the BOWS-2 image dataset. In the future, we would like to improve the entropy retained RDH scheme with enhanced embedding capacity without compromising image recoverability. S.P. : conceptualization, software, visualization, writing--original draft. V.M.M. : conceptualization, data curation, software, supervision, writing--original draft, writing--review and editing, project administration. Y.Z. : methodology, investigation, writing--original draft, supervision, project administration, funding acquisition, writing--review and editing, S.W. : methodology, formal analysis, writing--review and editing, funding acquisition. All authors have read and agreed to the published version of the manuscript. This paper is partially supported by SRM University-AP, Andhra Pradesh, India; MRC, UK (MC_PC_17171), the Royal Society, UK (RP202G0230), the Hope Foundation for Cancer Research, UK (RM60G0680), GCRF, UK (P202 PF11), the Sino-UK Industrial Fund, UK (RP202G0289), BHF, UK (AA/18/3/34220), LIAS, UK (P202 ED10, P202 RE969), the Data Science Enhancement Fund, UK (P202 RE237), Fight for Sight, UK (24 NN201); and the Sino-UK Education Fund, UK (OP202006); BBSRC, UK (RM32G0178B8). This paper is partially supported by SRM University-AP, Andhra Pradesh, India; MRC, UK (MC_PC_1717), the Royal Society, UK (RP202G0230), the Hope Foundation for Cancer Research, UK (RM60G0680), GCRF, UK (P202 PF11), the Sino-UK Industrial Fund, UK (RP202G0289), BHF, UK (AA/18/3/34220), LIAS, UK (P202 ED10, P202 RE969), the Data Science Enhancement Fund, UK (P202 RE237), Fight for Sight, UK (24 NN201); and the Sino-UK Education Fund, UK (OP202006); BBSRC, UK (RM32G0178B8). This paper is partially supported by SRM University-AP, Andhra Pradesh, India; MRC, UK (MC_PC_17171), the Royal Society, UK (RP202G0230), the Hope Foundation for Cancer Research, UK (RM60G0680), GCRF, UK (P202 PF11), the Sino-UK Industrial Fund, UK (RP202G0289), BHF, UK (AA/18/3/34220), LIAS, UK (P202 ED10, P202 RE969), the Data Science Enhancement Fund, UK (P202 RE237), Fight for Sight, UK (24 NN201); and the Sino-UK Education Fund, UK (OP202006); BBSRC, UK (RM32G0178B8). This paper is partially supported by SRM University-AP, Andhra Pradesh, India; MRC, UK (MC_PC_17171), the Royal Society, UK (RP202G0230), the Hope Foundation for Cancer Research, UK (RM60G0680), GCRF, UK (P202 PF111), the Sino-UK Industrial Fund, UK (RP202G0289), BHF, UK (AA/18/3/34220), LIAS, UK (P202 ED10, P202 RE969), the Data Science Enhancement Fund, UK (P202 RE237), Fight for Sight, UK (24 NN201); and the Sino-UK Education Fund, UK (OP202006); BBSRC, UK (RM32G0178B8). [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] Data hiding in complex-amplitude modulation using a digital micromirror device. _Opt. Lasers Eng._**2021**, _138_, 106455. [CrossRef]
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