Algorithm 1 HybridAugment+

Require: Image $I$(RGB photograph or grayscale radiograph), parameters $N_{min}$ = 2, $N_{max}$ = 10, $\sigma$ = 2, $M$ = 9, Minimal constant $\epsilon$

Ensure: Augmented image $I_{aug}$

/* Step 1: Contrast enhancement */

1: if $I$ is RGB photograph then

2:  $I_{gray}=(I_R+I_G+I_B)/3$                  /* Convert to grayscale */

3: else

4:  $I_{gray}$= $I$                       /* Radiograph already grayscale */

5: end if

6: $I_{eq} = CLAHE(I_{gray}, clip\_limit=2.0, grid\_size =(\mathrm{8,8}\left)\right)$         /* Local contrast enhancement */

0/* Step 2: Color balancing (photographs only) */

7: $H_{max}=⌈{\log }_2\mathrm{m}\mathrm{a}\mathrm{x}\left(I_{eq}\right)+1)⌉$                 /*Identify bit-depth */

8: $I_{max }=2^{H_{max}} -1$

9: if $I$ is RGB photograph then

10:  $I_{balanced}= GrayWorldColorBalance\left(I\right)$            /*Reduce illumination bias */

11:  $G=(I_{eq}+\epsilon )\oslash (I_{gray} +\epsilon )$                 /*Compute pixel-wise gain */

12:  $I_{base }= clip(I_{balanced} \otimes G,0,I_{max })$             /*Apply gain to all channels */

13: else

14:  $I_{base }=I_{eq}$

15: end if

0/* Step 3: Entropy computation */

16: Compute histogram $P\left(g_i\right)$ from $I_{eq}$ for i = 0, …, $2^{H_{max}}$ – 1

17: $H =-{\sum }_{i=0}^{2^{H_{max}}-1}P\left(g_i\right){\log }_{2}P\left(g_i\right)$               /*Shannon entropy in bits */

18: $H_{norm }=H/H_{max}$                     /*Normalize by maximum entropy */

/* Step 4: Adaptive operation count selection */

19: $p= N_{min}+(N_{max}-N_{min})\times (1-H_{norm})$             /*Expected operation count */

20: $N_{sample }=random.normal(mean=p,std = \sigma )$           /*Stochastic sampling */

21: $N_{final }= clip\left(round\right(N_{sample }), N_{min}, N_{max})$             /*Discrete operation count*/

/* Step 5: RandAugment with modality-specific operations */

22: $I_{aug}=RandAugment(I_{base}, N=N_{final}, M=M, operation\_pool=Pool(I\left)\right)$ /*Pool selected based on modality/*

/*Step 6: Color preservation (photographs only) */

23: if $I$ is RGB photograph then

24:  $I_{aug} = ColorPreservation(I_{aug}, I_{base })$            /*Mild gamut mapping/*

25: end if

26: return $I_{aug}$