39:
27:
177:), which involves rotating the negative and/or easel. Restoring parallelism to verticals (for instance) is easily done by tilting one plane, but if the focal length of the enlarger is not suitably chosen, the resulting image will have vertical distortion (compression or stretching). For correct perspective correction, the proper focal length (specifically, angle of view) must be chosen so that the enlargement replicates the perspective of the camera.
65:. This is a commonly accepted distortion in constructed perspective; perspective is based on the notion that more distant objects are represented as smaller on the page; however, even though the top of the cathedral tower is in reality further from the viewer than base of the tower (due to the vertical distance), constructed perspective considers only the horizontal distance and considers the top and bottom to be the same distance away;
85:
267:, which degrades the image quality, in particular blurring high-frequency detail. How significant this is depends on the original image resolution, degree of manipulation, print/display size, and viewing distance, and perspective correction must be traded off against preserving high-frequency detail.
243:
Other software with mathematical models on how lenses and different types of optical distortions affect the image can correct this by being able to calculate the different characteristics of a lens and re-projecting the image in a number of ways (including non-rectilinear projections). An example of
235:
tool, correcting vertical tilt (converging verticals) by stretching out the top; this is the "Distort
Transform" in Photoshop, and the "perspective tool" in GIMP. However, this introduces vertical distortion – objects appear squat (vertically compressed, horizontally extended) – unless the vertical
161:
technician can correct perspective distortion in the printing process. It is usually done by exposing the paper at an angle to the film, with the paper raised toward the part of the image that is larger, therefore not allowing the light from the enlarger to spread as much as the other side of the
239:
An alternative interface, found in
Photoshop (CS and subsequent releases) is the "perspective crop", which enables the user to perform perspective control with the cropping tool, setting each side of the crop to independently determined angles, which can be more intuitive and direct.
195:
have several "transform" options to achieve, with care, the desired control without any significant degradation in the overall image quality. Photoshop CS2 and subsequent releases includes perspective correction as part of its Lens
Distortion Correction Filter; DxO Optics Pro from
75:
occurs in photographs when the film plane is not parallel to lines that are required to be parallel in the photo. A common case is when a photo is taken of a tall building from ground level by tilting the camera backwards: the building appears to fall away from the camera.
123:(4x5 and up) cameras have this feature, as well as plane of focus control built into the camera body in the form of flexible bellows and moveable front (lens) and rear (film holder) elements. Thus any focal length lens mounted on a view camera or
236:
dimension is also stretched. This effect is minor for small angles, and can be corrected by hand, manually stretching the vertical dimension until the proportions look right, but is automatically done by specialized perspective transform tools.
279:" from 3D computer models, for use in promotional material. These have virtual cameras within to create the images, which normally have modifiers capable of correcting (or distorting) the perspective to the artist's taste. See
432:
212:, a free and open-source raw converter, includes horizontal and vertical perspective correction tools too. Note that because the mathematics of projective transforms depends on the
112:
Professional cameras where perspective control is important control the perspective at exposure by raising the lens parallel to the film. There is more information on this in the
335:
149:
options which allow perspective control and, in the case of a tilt/shift lens, plane of focus control, but only at a specific focal length.
72:
462:
185:
Digital post-processing software provides means to correct converging verticals and other distortions introduced at image capture.
391:
452:
200:
includes perspective correction; while GIMP (as of 2.6) does not include a specialized tool for correcting perspective, though a
457:
49:
is a procedure for composing or editing photographs to better conform with the commonly accepted distortions in constructed
276:
217:
38:
324:
Applied photographic optics: lenses and optical systems for photography, film, video, electronic and digital imaging
232:
142:
146:
101:
89:
50:
26:
20:
135:
201:
31:
252:
406:
365:
331:
327:
376:
302:
245:
68:
make all parallel lines (such as four horizontal edges of a cubic room) cross in one point.
297:
188:
256:
437:
446:
280:
264:
260:
213:
392:
Perspective and Barrel
Distortion Correction of Wide-angle Images in Adobe Photoshop
427:
292:
259:
due to the angle of the film/sensor plane to the subject. These transforms involve
128:
124:
120:
350:
57:
make all lines that are vertical in reality vertical in the image. This includes
209:
113:
107:
93:
422:
197:
158:
139:
62:
84:
58:
205:
255:
in the more distant areas of the subject, or the recovery of lost
83:
37:
25:
221:
192:
433:
Controlling perspective while cropping using
Photoshop software
251:
However these techniques do not enable the recovery of lost
438:
Correcting perspective using the Open Source Hugin software
322:
Ray, Sidney F. (2002). "63.6: Rectification printing".
216:, perspective tools require that the angle of view or
244:
this kind of software is the panorama creation suite
220:
be entered, though this can often be determined from
16:Technique for reducing perceived image distortion
428:Panorama Tools wiki page on perspective control
8:
377:Perspective Distortion Correction Tutorial
387:
385:
366:Hugin tutorial — Perspective correction
361:
359:
314:
231:to correct perspective using a general
145:, and Digital SLR camera systems have
131:can be used with perspective control.
96:, made for DSLR and 35mm SLR cameras.
7:
402:
400:
407:Perspective Adjustment in PhotoShop
351:Correcting Perspective in Photoshop
275:Architectural images are commonly "
14:
181:During digital post-processing
61:, vertical edges of walls and
34:showing perspective distortion
1:
218:35 mm equivalent focal length
147:PC, shift, or tilt/shift lens
479:
134:Some interchangeable lens
105:
99:
42:The same picture corrected
18:
463:Composition in visual art
233:projective transformation
409:, The Luminous Landscape
326:. Focal Press. pp.
165:The process is known as
102:Perspective control lens
19:Not to be confused with
453:Photographic techniques
271:In virtual environments
458:Perspective projection
169:, and is done using a
167:rectification printing
97:
73:Perspective distortion
43:
35:
21:Perspective distortion
87:
53:. The control would:
41:
29:
175:transforming printer
379:, Lone Star Digital
90:shift and tilt lens
47:Perspective control
32:Notre Dame de Reims
253:spatial resolution
229:commonly suggested
171:rectifying printer
98:
44:
36:
337:978-0-240-51540-3
88:24mm PC-E Nikkor
470:
410:
404:
395:
394:, Larry N. Bolch
389:
380:
374:
368:
363:
354:
348:
342:
341:
319:
303:Image distortion
230:
208:, is available.
478:
477:
473:
472:
471:
469:
468:
467:
443:
442:
419:
414:
413:
405:
398:
390:
383:
375:
371:
364:
357:
349:
345:
338:
321:
320:
316:
311:
298:Keystone effect
289:
273:
228:
189:Adobe Photoshop
183:
155:
153:In the darkroom
140:35 mm film
110:
104:
82:
24:
17:
12:
11:
5:
476:
474:
466:
465:
460:
455:
445:
444:
441:
440:
435:
430:
425:
418:
417:External links
415:
412:
411:
396:
381:
369:
355:
353:, Ken Rockwell
343:
336:
313:
312:
310:
307:
306:
305:
300:
295:
288:
285:
272:
269:
257:depth of field
206:EZ Perspective
182:
179:
154:
151:
100:Main article:
81:
78:
70:
69:
66:
15:
13:
10:
9:
6:
4:
3:
2:
475:
464:
461:
459:
456:
454:
451:
450:
448:
439:
436:
434:
431:
429:
426:
424:
423:Illustrations
421:
420:
416:
408:
403:
401:
397:
393:
388:
386:
382:
378:
373:
370:
367:
362:
360:
356:
352:
347:
344:
339:
333:
329:
325:
318:
315:
308:
304:
301:
299:
296:
294:
291:
290:
286:
284:
283:for details.
282:
281:3D projection
278:
270:
268:
266:
265:image scaling
262:
261:interpolation
258:
254:
249:
247:
241:
237:
234:
225:
223:
219:
215:
214:angle of view
211:
207:
203:
199:
194:
190:
186:
180:
178:
176:
172:
168:
163:
160:
152:
150:
148:
144:
141:
137:
136:medium format
132:
130:
129:press cameras
126:
122:
117:
115:
109:
103:
95:
91:
86:
79:
77:
74:
67:
64:
60:
56:
55:
54:
52:
48:
40:
33:
28:
22:
372:
346:
323:
317:
293:Anamorphosis
274:
250:
242:
238:
226:
187:
184:
174:
170:
166:
164:
156:
133:
125:field camera
121:large format
118:
111:
71:
46:
45:
210:RawTherapee
127:, and many
114:view camera
108:View camera
80:At exposure
51:perspective
30:Picture of
447:Categories
309:References
224:metadata.
162:exposure.
106:See also:
94:Nikon D700
116:article.
63:lampposts
287:See also
277:rendered
263:, as in
198:DxO Labs
159:darkroom
328:549–553
202:plug-in
92:on the
59:columns
334:
227:It is
246:Hugin
119:Most
332:ISBN
222:Exif
193:GIMP
191:and
143:SLR
449::
399:^
384:^
358:^
330:.
248:.
204:,
157:A
138:,
340:.
173:(
23:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
