N.A. ( Слушатель ) | |
05 апр 2010 15:45:16 |
Цитата: an_private
Точно-точно, производитель серой шкалы вообще не знает что производит - в документации указывает экспоненту, а на самом деле лепит линейную шкалу И десятки тысяч потребителей калибровочной шкалы до сих пор этого не заметили ;)
Хм, и почему это мне вспоминается пословица про "все не в ногу, одинкорнетсержант в ногу"
CodeGrinder ( Слушатель ) | |
05 апр 2010 19:06:21 |
Цитата: N.A. от 05.04.2010 15:45:16
N.A. ( Слушатель ) | |
05 апр 2010 20:18:52 |
Alex_B ( Слушатель ) | |
06 апр 2010 19:17:05 |
Цитата: N.A. от 05.04.2010 20:18:52
an_private ( Слушатель ) | |
06 апр 2010 19:48:43 |
Цитата: Alex_B от 06.04.2010 19:17:05
ЦитатаА что вам по кодаковской шкале не нравится? Это шкала (по русски - мишень, по-английски в докуменетации - target) для калибровки сканеров, сам ее держал в руках и НЕОДНОКРАТНО пользовался. И нее только ей, а еще и цветной, где квадратиков около 170, называется IT-8, гугль вам в помощь. Ты еще будешь меня денситометрии учить, сынок...
ЦитатаНейтральный средний серый (та самая Neitralized Mid Point) в координатах RGB 104-104-104, что близко весьма близко к 127-127-127, а с учетом белого 242-242 и черного 12-12-12 иили 24-24-24 так практически посередине.
CodeGrinder ( Слушатель ) | |
06 апр 2010 20:06:58 |
N.A. ( Слушатель ) | |
06 апр 2010 21:23:22 |
Цитата
Because the human visual perceptual system does not work in a linear manner, a non-linear curve must be applied to "stretch" the linear data from a DSLR camera to make the tonality of a photo match the way our visual system works. These non-linear adjustments are done by software inside the camera if the image is written to a JPEG file. If a raw file is saved in the camera, these non-linear adjustments are done in software later when the data is opened in an image processing program.
In the image examples seen above, a screen shot of Photoshop's Curves dialog has been included in the image so we can see a comparison between linear data and the same data with a non-linear curve applied to it. The curve in the dark image is linear, it is a straight line. The curve in the bright image shows the stretch that needs to be applied to the data to make it closer to our visual perception.
CodeGrinder ( Слушатель ) | |
06 апр 2010 21:33:03 |
Цитата: N.A. от 06.04.2010 21:23:22
Цитата
The linear data will usually look very dark and low in contrast compared to a normal photograph (see the image below).
Цитата
Because the human visual perceptual system does not work in a linear manner, a non-linear curve must be applied to "stretch" the linear data from a DSLR camera to make the tonality of a photo match the way our visual system works. These non-linear adjustments are done by software inside the camera if the image is written to a JPEG file. If a raw file is saved in the camera, these non-linear adjustments are done in software later when the data is opened in an image processing program.
N.A. ( Слушатель ) | |
09 апр 2010 15:05:40 |
Цитата
As you might expect, almost all digital cameras perform gamma correction (tone curve correction) to make the pictures look right on an approximately antilogarithmic screen display. Mainly, what they have to do is lighten the midtones a lot. Here's a typical conversion function, plotted with both linear and logarithmic scales for the sensor output:
For some purposes we need to know the actual numbers that came out of the image sensor, or numbers linearly proportional to them, without gamma correction. This enables us to do such things as measure the brightness of objects in the picture (important in astronomy) or subtract light from a known, unwelcome source leaving behind only the light we actually wanted. Related to the latter is dark frame subtraction, where we make two exposures, one with the lenscap on, and subtract them, so that the noise from hot pixels can be removed from the picture.
an_private ( Слушатель ) | |
09 апр 2010 15:03:25 |
Цитата: N.A. от 06.04.2010 21:23:22
N.A. ( Слушатель ) | |
09 апр 2010 15:27:48 |
Цитата
Linear Tone Curve Experiment
Hunger Memorial "As Shot"
This first image is exactly as shot. In the camera, the white balance was set to Daylight and the Picture Style was set to Standard.
Hunger Memorial Linear Dark
This is what happens when I reset everything to shot settings and only check the "linear" box below the tone curve.
Цитата: Alex_B от 06.04.2010 19:17:05
CodeGrinder ( Слушатель ) | |
09 апр 2010 15:38:45 |
Цитата: N.A. от 09.04.2010 15:27:48
Цитата: N.A. от 09.04.2010 15:27:48
N.A. ( Слушатель ) | |
09 апр 2010 16:05:14 |
CodeGrinder ( Слушатель ) | |
09 апр 2010 16:25:27 |
Цитата: N.A. от 09.04.2010 16:05:14
Цитата: N.A. от 09.04.2010 16:05:14
N.A. ( Слушатель ) | |
09 апр 2010 16:45:47 |