Target classification using SIFT sequence scale invariants

On the basis of scale invariant feature transform（SIFT） descriptors,a novel kind of local invariants based on SIFT sequence scale（SIFT-SS） is proposed and applied to target classification.First of all,the merits of using an SIFT algorithm for target classification are discussed.Secondly,the scales of SIFT descriptors are sorted by descending as SIFT-SS,which is sent to a support vector machine（SVM） with radial based function（RBF） kernel in order to train SVM classifier,which will be used for achieving target classification.Experimental results indicate that the SIFT-SS algorithm is efficient for target classification and can obtain a higher recognition rate than affine moment invariants（AMI） and multi-scale auto-convolution（MSA） in some complex situations,such as the situation with the existence of noises and occlusions.Moreover,the computational time of SIFT-SS is shorter than MSA and longer than AMI.

Multiband camouflage design with thermal management

Although the effective“stealth”of space vehicles is important,current camouflage designs are inadequate in meeting all application requirements.Here,a multilayer wavelength-selective emitter is demonstrated.It can realize visible light and dual-band mid-infrared camouflage with thermal control management in two application scenarios,with better effect and stronger radiation cooling capability,which can significantly improve the stealth and survivability of space vehicles in different environments.The selective emitter demonstrated in this paper has the advantages of simple structure,scalability,and ease of large-area fabrication,and has made a major breakthrough in driving multiband stealth technology from simulation research to physical verification and even practical application.

Erratum to:High-throughput fast full-color digital pathology based on Fourier ptychographic microscopy via color transfer [Sci. China-Phys. Mech. Astron. 64(11), 114211 (2021)]

In this paper[1],Figure 5(a)is mistakenly used with the figure of ground truth,which is taken and stitched by 10×/0.3NA objective and the operations have been detailed in the main text.The correction is as follows(Figure 1).This error does not affect the conclusion of this paper.The authors have also checked other figures such as Figure 6,and they are used correctly.

Rapid full-color Fourier ptychographic microscopy via spatially filtered color transfer

Full-color imaging is of critical importance in digital pathology for analyzing labeled tissue sections.In our previous cover story[Sci.China:Phys.,Mech.Astron.64,114211(2021)],a color transfer approach was implemented on Fourier ptychographic microscopy(FPM)for achieving high-throughput full-color whole slide imaging without mechanical scanning.The approach was able to reduce both acquisition and reconstruction time of FPM by three-fold with negligible trade-off on color accuracy.However,the method cannot properly stain samples with two or more dyes due to the lack of spatial constraints in the color transfer process.It also requires a high computation cost in histogram matching of individual patches.Here we report a modified full-color imaging algorithm for FPM,termed color-transfer filtering FPM(CFFPM).In CFFPM,we replace the original histogram matching process with a combination of block processing and trilateral spatial filtering.The former step reduces the search of the solution space for colorization,and the latter introduces spatial constraints that match the low-resolution measurement.We further adopt an iterative process to refine the results.We show that this method can perform accurate and fast color transfer for various specimens,including those with multiple stains.The statistical results of 26 samples show that the average root mean square error is only 1.26%higher than that of the red-green-blue sequential acquisition method.For some cases,CFFPM outperforms the sequential method because of the coherent artifacts introduced by dust particles.The reported CFFPM strategy provides a turnkey solution for digital pathology via computational optical imaging.

High-throughput fast full-color digital pathology based on Fourier ptychographic microscopy via color transfer

The usage of full-color imaging in digital pathology produces significant results.Compared with a grayscale image or a pseudocolor image containing contrast information,a full-color image can identify and detect the target object better with color texture information.Fourier ptychographic microscopy(FPM)is a high-throughput computational imaging technique that breaks the tradeoff between high resolution(HR)and a large field of view.It also eliminates the artifacts of scanning and stitching in digital pathology and improves its imaging efficiency.However,the conventional full-color digital pathology based on FPM is still time-consuming because of the repeated experiments with tri-wavelengths.A color transfer FPM approach termed“CFPM”was reported.The color texture information of a low-resolution full-color pathologic image is directly transferred to the HR grayscale FPM image captured by only a single wavelength.Both of the color space of FPM based on the standard CIE-XYZ color model and the display based on the standard RGB color space were established.Different FPM colorization schemes were analyzed and compared with 30 biological samples.Three types of evaluation approaches were provided,including the root-mean-square error(RMSE),the difference maps,and the image histogram cosine similarity.The average RMSE values of the conventional method and CFPM compared with the ground truth were 5.3%and 5.7%,respectively.Therefore,the reconstruction time is significantly reduced by 2/3 with the sacrifice of precision of only 0.4%.The CFPM method is also compatible with advanced fast FPM approaches to further reduce computation time.