Denoised results of the “House” image at different stages.

<p>(a) Original House image; (b) Noisy image; (c) Denoised result in the first stage; (d) Denoised result in the second stage; (e) Denoised result in the third stage; (f) Denoised result in the fourth stage.</p

STDs of three ROIs for LDCT, SDCT, and processed LDCT images of a 53-year-old female patient with liver tumor.

<p>STDs of three ROIs for LDCT, SDCT, and processed LDCT images of a 53-year-old female patient with liver tumor.</p

Denoising results for a 61-year-old female patient with liver tumor.

<p>The first column from (a) to (e) shows the SDCT image, LDCT image, and images denoised with AT-PCA, NLM and KSVD, respectively. Red circles and numbers denote positions of tumors (numbers 1, 2, 3, 4, 5) and the backgrounds (numbers 6 and 7). The second column from (a’) to (e’) shows the zoomed regions corresponding to (a) to (e).</p

Diagrammatic sketch for hunting the adaptive searching window.

<p>Diagrammatic sketch for hunting the adaptive searching window.</p

Denoising results for a 56-year-old male patient with multiple hepatic metastases (slice 2).

<p>The first column from (a) to (e) shows the SDCT image, LDCT image, and images denoised with AT-PCA, NLM, and KSVD, respectively. The second column from (a’) to (e’) shows the zoomed regions corresponding to (a) to (e).</p

Denoising results for a 53-year-old female patient with liver tumor.

<p>The first column from (a) to (e) shows the SDCT image, the LDCT image, as well as the images denoised with AT-PCA, NLM and KSVD, respectively. Red circles and numbers denote positions of tumors (numbers 1 and 2) and the background (number 3). The second column from (a’) to (e’) shows the zoomed regions corresponding to (a) to (e).</p

Denoising results with three parameters and two stages.

<p>(a) LDCT image; (b) SDCT image; (c), (f), and (i) are the LDCT images denoised with <i>P</i> = 2, <i>P</i> = 3, and <i>P</i> = 4 in the first stage, respectively; (d), (g), and (j) are the LDCT images denoised with <i>P</i> = 2, <i>P</i> = 3, and <i>P</i> = 4 in the second stage, respectively; (e), (h), and (k) are the zoomed regions specified in (a).</p

Standard deviations of different ROIs for the original image, noisy image, and denoised images in the four stages.

<p>Standard deviations of different ROIs for the original image, noisy image, and denoised images in the four stages.</p

STDs of seven ROIs for LDCT, SDCT, and processed LDCT images of a 61-year-old female patient with liver tumor.

<p>STDs of seven ROIs for LDCT, SDCT, and processed LDCT images of a 61-year-old female patient with liver tumor.</p

MSE, SNR, PSNR, SSIM, and <i>β</i> results of the noisy “House” image and denoised images in the four stages.

<p>MSE, SNR, PSNR, SSIM, and <i>β</i> results of the noisy “House” image and denoised images in the four stages.</p