Table 10 Chi-square test results.

From: Novel structures of chaos-based parallel multiple image encryption and FPGA implementation

\(\chi ^2\) of encrypted images in the exemplar simulation using Structure 1 in Fig. 1a

\(N_e\)

1

2

3

4

5

Channel

R

G

B

R

G

B

R

G

B

R

G

B

R

G

B

Baboon

225.024

274.968

274.831

283.294

278.586

238.726

270.159

236.399

276.024

266.733

272.489

244.002

278.942

256.361

231.366

Flowers

287.042

241.166

229.438

248.549

261.338

287.673

266.248

251.737

252.365

264.305

277.905

251.847

266.132

276.033

250.014

Peppers

271.232

246.325

226.382

272.219

241.743

227.020

212.012

246.864

245.899

256.662

267.964

239.662

269.368

245.315

271.356

Goldhill

256.172

223.146

269.022

255.493

268.755

258.332

225.218

269.318

278.298

227.722

253.505

252.721

241.462

284.386

258.382

Black

258.190

275.968

266.930

242.293

266.213

Boats

232.903

244.562

246.557

264.909

299.651

Clock

237.016

251.578

260.742

272.211

270.281

White

267.814

262.724

283.123

258.653

215.717

Average

251.292 (Pass)

259.785 (Pass)

255.493 (Pass)

257.099 (Pass)

261.311 (Pass)

\(\chi ^2\) of encrypted images in the exemplar simulation using Structure 2 in Fig. 1b

\(N_e\)

1

2

3

4

5

Channel

R

G

B

R

G

B

R

G

B

R

G

B

R

G

B

Baboon

226.044

260.122

260.563

236.239

277.043

263.742

248.465

235.881

274.929

253.086

251.480

301.811

286.812

227.428

234.404

Flowers

267.646

205.408

292.405

248.334

287.783

259.227

295.285

231.308

252.419

273.642

233.257

262.540

243.087

282.856

227.670

Peppers

263.356

269.438

255.138

234.802

251.378

280.429

220.387

260.395

249.479

255.202

249.676

290.457

270.369

251.735

220.364

Goldhill

266.360

269.895

268.893

280.378

249.177

232.245

280.120

252.197

253.164

273.825

235.658

294.107

304.127

255.396

238.926

Black

241.076

251.418

276.914

230.526

216.151

Boats

233.224

262.757

250.315

261.549

230.815

Clock

240.406

222.055

244.469

255.430

273.727

White

211.514

240.997

238.493

261.427

245.593

Average

251.968 (Pass)

254.875 (Pass)

254.014 (Pass)

261.480 (Pass)

250.591 (Pass)

\(\chi ^2\) of encrypted images in the exemplar simulation using Structure 3 in Fig. 1c

\(N_e\)

1

2

3

4

5

Channel

R

G

B

R

G

B

R

G

B

R

G

B

R

G

B

Baboon

258.603

235.392

280.506

253.197

276.450

265.444

259.392

251.960

233.137

243.712

258.878

274.037

269.745

261.978

270.443

Flowers

235.692

296.968

220.527

219.684

245.689

273.235

295.500

219.682

262.359

205.923

232.756

231.313

267.801

254.817

233.418

Peppers

265.548

249.135

266.452

220.354

227.686

267.629

255.489

275.327

256.135

247.028

255.613

239.657

228.358

273.516

265.902

Goldhill

231.418

249.874

218.995

222.326

247.528

237.083

267.491

278.048

203.367

241.728

271.877

219.586

245.952

265.682

253.891

Black

203.720

245.266

267.113

266.415

256.545

Boats

281.506

257.516

273.678

286.019

263.912

Clock

237.133

255.656

218.313

186.922

234.008

White

235.127

247.135

258.162

240.050

259.806

Average

247.912 (Pass)

247.617 (Pass)

254.697 (Pass)

243.845 (Pass)

256.611 (Pass)