downstream noise

Russian translation: «нисходящий» шум

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18:11 Mar 12, 2018
English to Russian translations [PRO]
Tech/Engineering - Photography/Imaging (& Graphic Arts) / динамический диапазон и шум в цифровой фотографии/процессы, происходящие на матрице
English term or phrase: downstream noise
This is accomplished by multiplying by the gain g=U/G , the conversion factor between electrons and ADU; here, U is a constant (the so-called universal gain) and G is the ISO setting.
When this is done, the opposite trend is observed -- read noise goes down with ISO in electron equivalents:
(R in electrons)2 = [ g * (R in ADU) ]2 = U2 (R02 + R12/ G2)
The reason for this decrease is the decreasing influence of downstream noise R1 with amplification; in referring the noise back to input equivalents, the downstream noise gets divided by the ISO gain, and hence becomes smaller and smaller at high ISO, while the upstream noise didn't know about any amplification and remains constant in input-referred units.

https://theory.uchicago.edu/~ejm/pix/20d/tests/noise/noise-p...

Я не настолько техник, к сожалению, чтобы точно понять, идёт ли речь о шуме на выходе или о шуме, идущем вниз по схеме.
Заранее признателен.
Boris Filichkin
Italy
Local time: 05:18
Russian translation:«нисходящий» шум
Explanation:
Из Вашего источника: "...noise downstream of the main ISO amplification...". То есть шум вниз по течению после главного усиления ISO, если более-менее дословно.

Downstream noise — шум, вносимый элементами, находящимися после усилителя ISO.

---

Вот здесь схема в конце раздела ISO-Variant Cameras с разделением элементов на upstream и downstream — https://petapixel.com/2017/03/22/find-best-iso-astrophotogra...

"Some noise is random with every shot (shot noise) and some noise is produced consistently by the camera’s sensor (upstream read noise) or produced by the electronics after the sensor’s signal has been amplified (downstream read noise)".

По следующей ссылке перевод статьи, там термины переведены как "восходящий" и "нисходящий" шумы — https://photo-monster.ru/lessons/read/kak-podobrat-iso-dlya-...

---

Ещё источник — http://dslr-astrophotography.com/iso-dslr-astrophotography/
Схожая схема в разделе ISO and Read Noise. Там два усилителя: аналоговый, в upstream, и цифровой, находящийся в downstream части схемы.

"Read noise consists of two different parts; the so called upstream and downstream noise. The upstream noise is all the noise that occurs in the electronics before the actual Analog-to-Digital conversion in the ADC. The downstream noise is anything from that point onward, which of course includes the noise of the ADC itself.
...ISO setting controls the amplification of the output signal of the sensor. This means that all the upstream noise will be amplified with it, while the downstream noise remains consistent".

Из Вашего источника:
"The two-stage amplification employed by Canon gives a bit more information as to what portion of the read noise can be attributed to different circuit components in its high-end cameras. Because of the second stage of amplification, one has separate information on how much of the read noise is due to noise in the main ISO amplification and how much is downstream from it in the secondary amplification and ADC. One sees from the table that the dominant noise at low ISO arises from the main ISO amplifier noise R1, with a smaller contribution R2 from the components downstream from this amplifier and a negligible contribution from the sensor readout noise R0".

---

Upstream noise — шум, вносимый элементами (матрица, аналоговый усилитель ISO, может, ещё и др.), находящимися до АЦП.
Downstream noise — шум, вносимый элементами, начиная с АЦП (аналого-цифрового преобразователя, ADC) и далее.

--------------------------------------------------
Note added at 3 hrs (2018-03-12 21:57:46 GMT)
--------------------------------------------------

"Now remember that the ISO setting controls the amplification of the output signal of the sensor. This means that all the upstream noise will be amplified with it, while the downstream noise remains consistent. In other words; we gain SNR! And this of course is a good thing right?

So should we choose very high ISOs then? Well, not so fast. As always, things aren’t quite that easy;).

There is a limit to the gain you will get, which is determined by the downstream noise. Once the upstream noise gets high enough OR the downstream noise gets close to zero, the upstream noise will simply swamp out the downstream noise, making it irrelevant. So once we move past this point, the read noise will be scaling linearly with the signal, gaining us nothing anymore in terms of SNR; If you double the signal, you’ll double the noise".

http://dslr-astrophotography.com/iso-dslr-astrophotography/
Selected response from:

didimblog
Russian Federation
Local time: 07:18
Grading comment
Большое спасибо за исчерпывающий ответ!
4 KudoZ points were awarded for this answer



Summary of answers provided
3«нисходящий» шум
didimblog
3выходной шум
Enote


Discussion entries: 4





  

Answers


5 mins   confidence: Answerer confidence 3/5Answerer confidence 3/5
выходной шум


Explanation:
Или шум на выходе
Шум не может распространяться обратно (вниз) по схеме. Они просто пересчитывают его на вход

Enote
Local time: 06:18
Native speaker of: Native in RussianRussian
PRO pts in category: 16
Notes to answerer
Asker: Понятно, спасибо Тогда логичнее "шум на выходе", иначе было бы output noise

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2 hrs   confidence: Answerer confidence 3/5Answerer confidence 3/5
«нисходящий» шум


Explanation:
Из Вашего источника: "...noise downstream of the main ISO amplification...". То есть шум вниз по течению после главного усиления ISO, если более-менее дословно.

Downstream noise — шум, вносимый элементами, находящимися после усилителя ISO.

---

Вот здесь схема в конце раздела ISO-Variant Cameras с разделением элементов на upstream и downstream — https://petapixel.com/2017/03/22/find-best-iso-astrophotogra...

"Some noise is random with every shot (shot noise) and some noise is produced consistently by the camera’s sensor (upstream read noise) or produced by the electronics after the sensor’s signal has been amplified (downstream read noise)".

По следующей ссылке перевод статьи, там термины переведены как "восходящий" и "нисходящий" шумы — https://photo-monster.ru/lessons/read/kak-podobrat-iso-dlya-...

---

Ещё источник — http://dslr-astrophotography.com/iso-dslr-astrophotography/
Схожая схема в разделе ISO and Read Noise. Там два усилителя: аналоговый, в upstream, и цифровой, находящийся в downstream части схемы.

"Read noise consists of two different parts; the so called upstream and downstream noise. The upstream noise is all the noise that occurs in the electronics before the actual Analog-to-Digital conversion in the ADC. The downstream noise is anything from that point onward, which of course includes the noise of the ADC itself.
...ISO setting controls the amplification of the output signal of the sensor. This means that all the upstream noise will be amplified with it, while the downstream noise remains consistent".

Из Вашего источника:
"The two-stage amplification employed by Canon gives a bit more information as to what portion of the read noise can be attributed to different circuit components in its high-end cameras. Because of the second stage of amplification, one has separate information on how much of the read noise is due to noise in the main ISO amplification and how much is downstream from it in the secondary amplification and ADC. One sees from the table that the dominant noise at low ISO arises from the main ISO amplifier noise R1, with a smaller contribution R2 from the components downstream from this amplifier and a negligible contribution from the sensor readout noise R0".

---

Upstream noise — шум, вносимый элементами (матрица, аналоговый усилитель ISO, может, ещё и др.), находящимися до АЦП.
Downstream noise — шум, вносимый элементами, начиная с АЦП (аналого-цифрового преобразователя, ADC) и далее.

--------------------------------------------------
Note added at 3 hrs (2018-03-12 21:57:46 GMT)
--------------------------------------------------

"Now remember that the ISO setting controls the amplification of the output signal of the sensor. This means that all the upstream noise will be amplified with it, while the downstream noise remains consistent. In other words; we gain SNR! And this of course is a good thing right?

So should we choose very high ISOs then? Well, not so fast. As always, things aren’t quite that easy;).

There is a limit to the gain you will get, which is determined by the downstream noise. Once the upstream noise gets high enough OR the downstream noise gets close to zero, the upstream noise will simply swamp out the downstream noise, making it irrelevant. So once we move past this point, the read noise will be scaling linearly with the signal, gaining us nothing anymore in terms of SNR; If you double the signal, you’ll double the noise".

http://dslr-astrophotography.com/iso-dslr-astrophotography/

didimblog
Russian Federation
Local time: 07:18
Native speaker of: Native in RussianRussian
PRO pts in category: 8
Grading comment
Большое спасибо за исчерпывающий ответ!
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