The document discusses image resource limits on iOS devices. Decoded GIF, PNG, and TIFF images are limited to 3 megapixels for devices with less than 256MB of RAM, while JPEG images have a higher limit of 32 megapixels due to chroma subsampling that reduces file size. Images greater than 5 megapixels may exceed memory limits.

2. 2.1

4. 2012

5. 모바일

6. 브라우저

7. 점유율

8.
2.2

10. 이미지

11. 리소스

12. 제약

13. 살펴보기

14.
3.1

16. 이가

17. 없으면

18. 잇몸으로…⋯

19.
4.1

21. 이렇게

22. 합니다.

23.
5.1

25. DEMO

26.
5.2

28. 소소한

29. Tips

38. 500

39. x

40. 29400

42. 500

43. x

44. 29400

45.
=

46. 44,100,000

47. px

49. 500

50. x

51. 29400

52.
=

53. 44,100,000

54. px

55.
=

56. 44

57. Mpx

59. 500

60. x

61. 29400

62.
=

63. 44,100,000

64. px

65.
=

66. 44

67. Mpx

72. decoded GIF,

73. PNG,

74. and

75. TIFF

76. images

77. is

78. 3

79. megapixels

80. less

81. than

82. 256

83. MB

84. RAM

85.
5

86. megapixels

87. greater

88. or

89. equal

90. than

91. 256

92. MB

93. RAM
JPEG

94. is

95. 32

96. megapixels

97. subsampling

98.
sixteenth

100.
2

101. megapixels

102. are

103. subsampled

104. Know

105. iOS

106. Resource

107. Limits

108.
•

109. The

110. maximum

111. size

112. for

113. decoded

114. GIF,

115. PNG,

116. and

117. TIFF

118. images

119. is

120. 3

121. megapixels

122. for

123. devices

124. with

125. less

126. than

127. 256

128. MB

129. RAM

131. and

132. 5

133. megapixels

134. for

135. devices

136. with

137. greater

138. or

139. equal

140. than

141. 256

142. MB

143. RAM.

145.
• width

146. *

147. height

148. ≤

149. 3

150. *

151. 1024

152. *

153. 1024

154. for

155. devices

156. with

157. less

158. than

159. 256

160. MB

161. RAM

163.
• The

164. maximum

165. decoded

166. image

167. size

168. for

169. JPEG

170. is

171. 32

172. megapixels

173. using

174. subsampling

175.
JPEG

176. images

177. can

178. be

179. up

180. to

181. 32

182. megapixels

183. due

184. to

185. subsampling,

186. which

187. allows

188. JPEG

189. images

190. to

191. decode

192. to

193. a

194. size

195. that

196. has

197. one

198. sixteenth

200.
the

201. number

202. of

203. pixels.

204. JPEG

205. images

206. larger

207. than

208. 2

209. megapixels

210. are

211. subsampled—―that

212. is,

213. decoded

214. to

215. a

216. reduced

217. size.

220.
• The

221. maximum

222. size

223. for

224. a

225. canvas

226. element

227. is

228. 3

229. megapixels

230. for

231. devices

232. with

233. less

234. than

235. 256

236. MB

237. RAM

240. and

241. 5

242. megapixels

243. for

244. devices

245. with

246. greater

247. or

248. equal

249. than

250. 256

251. MB

252. RAM

254.
출처

255. :

257.
http://developer.apple.com/library/ios/#DOCUMENTATION/AppleApplications/Reference/SafariWebContent/CreatingContentforSafarioniPho
ne/CreatingContentforSafarioniPhone.html

258.
참고

259. :

261. (NULI

262. NHN

264. 웹표준)

265.
http://html.nhndesign.com/blog/17978

267. .

268. =

269. 256M
#ifdef

270. ANDROID_LARGE_MEMORY_DEVICE

275. #define

276. MIN_RLE_ALLOC_SIZE

286. (2*1024*1024)

287.
#define

288. MIN_RLE_ALLOC_SIZE

298. (8*1024*1024)

299. #define

300. MAX_SIZE_BEFORE_SUBSAMPLE

303. (2*1024*1024)

304.
#define

305. MAX_SIZE_BEFORE_SUBSAMPLE

308. (8*1024*1024)

310. //

311. flag

312. to

313. tell

314. us

315. when

316. we're

317. on

318. a

319. large-ram

320. device

321. (e.g.

322. =

323. 256M)

324.
#ifdef

325. ANDROID_LARGE_MEMORY_DEVICE

330. //

331. don't

332. use

333. RLE

334. for

335. images

336. smaller

337. than

338. this,

339. since

340. they

341. incur

342. a

343. drawing

344. cost

345. #else

350. //

351. (and

352. don't

353. work

354. as

355. patterns

356. yet)

357. we

358. only

359. want

360. to

361. use

362. RLE

363. when

364. we

365. must

370. #define

371. MIN_RLE_ALLOC_SIZE

381. (2*1024*1024)

386. #define

387. MIN_RLE_ALLOC_SIZE

397. (8*1024*1024)

402. #define

403. MAX_SIZE_BEFORE_SUBSAMPLE

406. (2*1024*1024)

413. //

414. see

415. dox

416. for

417. computeMaxBitmapSizeForCache()

422. //

423. tries

424. to

425. minimize

426. memory

427. usage

428. (i.e.

429. demote

430. opaque

431. 32bit

432. -

433. 16

437. #define

438. MAX_SIZE_BEFORE_SUBSAMPLE

441. (8*1024*1024)

446. static

447. const

448. SkBitmap::Config

449. gPrefConfigTable[6]

450. =

451. {

495. …⋯

496. 생략

501. //

502. preserve

503. quality

504. for

505. 24/32bit

506. src

507. };

512. static

513. const

514. SkBitmap::Config

515. gPrefConfigTable[6]

516. =

517. {

518. #endif

527. SkBitmap::kIndex8_Config,

534. //

535. src:

536. index,

537. opaque

547. SkBitmap::kIndex8_Config,

554. //

555. src:

556. index,

557. alpha

558. /*

560. Images

561. larger

562. than

563. this

564. should

565. be

566. subsampled.

567. Using

568. ashmem,

569. the

577. SkBitmap::kRGB_565_Config,

583. //

584. src:

585. 16bit,

586. opaque

591. pixels

592. will

593. be

594. purged

595. as

596. needed,

597. so

598. this

599. value

600. can

601. be

602. pretty

603. large.

604. M

612. SkBitmap::kARGB_8888_Config,

616. //

617. src:

618. 16bit,

619. alpha

621. (promote

622. to

623. 32bit)

628. it

629. too

630. small

631. hurts

632. image

633. quality

634. (e.g.

635. abc.com

636. background).

637. 2Meg

638. w

646. SkBitmap::kARGB_8888_Config,

650. //

651. src:

652. 32bit,

653. opaque

658. the

659. sites

660. I've

661. tested,

662. but

663. if

664. we

665. hit

666. important

667. sites

668. that

669. need

670. more,

671. w

679. SkBitmap::kARGB_8888_Config,

683. //

684. src:

685. 32bit,

686. alpha

691. should

692. try

693. increasing

694. it

695. and

696. see

697. if

698. it

699. has

700. negative

701. impact

702. on

703. perform

707. };

712. (i.e.

713. we

714. end

715. up

716. thrashing

717. because

718. we

719. need

720. to

721. keep

722. decoding

723. imag

727. been

728. purged.

729.
출처

730. :

734.
git

735. clone

736. https://android.googlesource.com/platform/external/webkit

741. Perhaps

742. this

743. value

744. should

745. be

746. some

747. fraction

748. of

749. the

750. available

751. RAM...

752.
*/

753.
static

754. size_t

755. computeMaxBitmapSizeForCache()

756. {

758. IOS

759. Android

760.
Embed

761. Browser

762. Safari

763. Android

764. Browser

765.
Layout

766. Engine

767. WebKit

768. WebKit

769.
Max.

771. 3

772. M

773. ­–

774. 5

775. M

777. 2

778. M

779. ­–

780. 8

781. M

782.
Decoded

783. Image

784. Pixels

785. (jpeg

786. 32

787. M)

788.
Force

789. Resize

790. (subsamplin jpeg

791. 2

792. M

793. over

794. 2

795. or

796. 8

797. M

798. over

799.
g)

800.
Huristic

801. 6

802. M

803. over

804. -

806. 500

807. x

808. 29400

809.
=

810. 44,100,000

811. px

812.
44

813. Mpx

815. 2-8Mpx

824. XSU

825. (min/maX

826. Scan

827. Unit)

829. XSU

830. XSU

831. XSU

832. XSU

833.
XSU

834. XSU

835. XSU

836. …⋯N

838. XSU

839. XSU

840. XSU

841. XSU

842.
XSU

843. XSU

844. XSU

845. …⋯N

847. Thresh
old

848. Val
ue

849.
XSU

850.
Contents

851. ROI

852. Graph

854. Callback

855.
C.

856. ROI

857. Handler

858.
Graph

859.
Image

860.
Callback

862. Image

863. Partitioni
ng

869. yjstyle@gmail.com