Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

A series of experimental tests are implemented for a wide range of the angle of reflection. The interesting finds are revealed as the angle of 45^0 can change the color properties. As descriptions in the conclusion section, the finds have important applications. The manuscript is well-written, and the experimental results are analyzed properly. I would like to recommend the current version for publication.  The only comment is that the quality of figure 3 is not good, please improve it to be publishable.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The paper presents a well-structured investigation into the angular dependence of spectral reflectance for glossy ceramic color standards. The experimental design is sound, and the results clearly demonstrate how specular reflection disrupts colorimetric parameters around the mirror angle. I support publishing, however, the manuscript would benefit from more explicit discussion of the practical implications for routine calibration work. For example, while the authors mention “extending the laboratory’s competences,” they do not quantify how much uncertainty is introduced when a 45°:0° geometry is assumed for these standards. Adding an uncertainty budget or at least a worst-case ΔE value that could propagate to customer instruments would strengthen the relevance. Additionally, the normalization procedure used to “eliminate the effect of weakening signal” should be described in greater detail in the Methods section; reviewers will want to know whether this step could bias the derived color coordinates. Minor language issues (e.g., “the color of its surface,” “the set of ceramic reference standards ‘Glossy Ceramic Color Standards’ DM05”) should be polished for clarity. Also, this work (multi-angle characterization and spectral reflection) in my opinion is belong to the emerging concept of high-dimensional structured light, the authors need to consider to include the recent perspective paper “Towards higher-dimensional structured light” Finally, the captions for Figures 9 and 10 are truncated; complete them so that readers can interpret the curves without referring back to the main text.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

I would like to thank the authors for composing this manuscript. Overall, I believe the research presented lacks enough scientific merit for the research community to be considered for publication in Photonics. The main reasons are listed below:

 

• The research focuses on a specific color standard, dedicated to a specific instrument located at a certain office. There is no evidence suggesting that the findings in the paper can be used by other researchers in their projects studying reflectometry or similar experiments.  
• There is very little scientific discussion around the reasons behind authors findings. The manuscript mostly contains report of certain observations without enough elaboration.
• The main conclusion of the manuscript is that certain color standards can not be characterized correctly under certain angles. I find this not to be a significant enough finding to be included in a research article.  

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

I would like to thank the authors for their comprehensive response to my comments in their cover letter. The responses and revisions made are satisfactory.