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03-05-2018, 11:30 PM   #16
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QuoteOriginally posted by angerdan Quote
Not gone, just revised:
OK, it looks like they reposed it, with some modification. The two changes that I see that interested me were....
  • In the side by side chipped out image example, the ISO was originally 25600, and is now 51200.
  • The original statement has been slightly modified to "The accelerator chip is supposed to be most effective at low and mid ISOs. It retains detail and improves noise and DR.".
In essence, they are returning to emphasizing higher ISO values, while dropping claims about detail retention, along with improved noise and DR.

Just waiting for reviews and examples to try to figure out what benefits there are for me.



03-06-2018, 04:48 AM   #17
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One day, hopefully Ricoh will release a paper / tech note specifically about the Accelerator chip.

QuoteOriginally posted by clackers Quote
The parent company Ricoh has made semiconductor components in the past
Indeed they have. The main chips for the Nintendo Entertainment System spring to mind.

More recently, of course, the 86k pixel RGB imaging sensor used in the K-3 series, K-1, 645Z, and KP is also a Ricoh-made chip.

Ricoh, in fact, still have a huge IC product line:

RICOH Electronic Devices Co., Ltd. - Official Website
03-21-2019, 01:49 AM   #18
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Compared noise histograms of the K1 and K1 II at ISO 204000 in the dark. It's interesting, the K1 noise histogram is single sided around Zone 1-2, and the K1II histogram is Gaussian around Zone 3. That means the K1 II pulls deep shadow signal out of the dark and eventually does some kind of low pass filtering only applied to low significance bits, cancelling some of the read noise in low bit levels only. It's basically a pseudo Nikon dual gain done digitally by the accelerator chip (hence no extra cost of using a new dual gain sensor), thus a partial (not total) benefit of dual gain, it robs some micro-contrast but doesn't affect sharp edges. K1 II the D range is increased 1 or 2 stops, color depth up by 1 to 2 bits, this is what helps getting around 10-9bits color depth between ISO800 and ISO3200 and still getting visible image detail at ISO800000. According to Photo-2-photo, the hardware pull of deep shadows happens to switch around ISO640 for the K1II , KP and K70, thus not programmable by in camera software option.

Last edited by biz-engineer; 03-21-2019 at 02:45 AM.
03-21-2019, 08:08 AM - 1 Like   #19
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This thread needs more Accelerator Chip pictures:

K-70 Accelerator unit:


KP Accelerator unit:


K-1 II Accelerator Unit (with PRIME IV imaging chip):


03-27-2019, 07:26 PM   #20
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so this chip is somekind of digital processing to photo output?
03-28-2019, 01:02 PM   #21
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QuoteOriginally posted by KoolKool Quote
so this chip is somekind of digital processing to photo output?
As you can see from the images above, the job of this chip is to work closely with the imaging engine chip to boost it's capabilities and horsepower.

All digital cameras need to process the data coming in from the imaging sensor before they can produce an image file that you can save onto a SD card. Many chips play a role.
03-28-2019, 01:22 PM   #22
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QuoteOriginally posted by KoolKool Quote
so this chip is somekind of digital processing to photo output?
You can view it as a post-processor for the sensor, or as a pre-processor for the PRIME processor.
This 'accelerator' "cleans" data as it flows from the sensor to the PRIME; Ricoh hasn't told us what else it does.

04-03-2019, 11:18 PM   #23
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As a hardware and software developer since the first days of microprocessors, I can't see what this chip does which could not be done in software.

Does it work in the analog or the digital domain? If the former then it might be doing what the old Dolby B did for audio: apply a nonlinear amplification to the signal, which then allows a better dynamic range to be extracted from the subsequent A-D converter.

Where is the A-D converter?
04-03-2019, 11:45 PM   #24
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QuoteOriginally posted by peterh337 Quote
Where is the A-D converter?
I’m under the impression that the A/D converters are all located on the main sensor.
04-04-2019, 01:07 AM   #25
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That is certainly the case for some sensors lower down the market; their output is purely digital. I have no idea about these higher end sensors.

If the sensor does indeed output digital data (probably 14 bit; a lot of the ARM processors have a 14 bit digital camera interface which can transfer ~50mbytes/sec) then this image processing chip cannot be doing anything which the camera's software could not do. It might do it a lot faster...

Last edited by peterh337; 04-04-2019 at 01:16 AM.
04-04-2019, 10:01 AM   #26
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QuoteOriginally posted by peterh337 Quote
this image processing chip cannot be doing anything which the camera's software could not do. It might do it a lot faster...
Not necessarily.
We don't know how this unit is structured.

It could possibly be a Gate Array or some other specialized hardware - or a Digital Signal Processor.
Back when I worked on digital radios, the "modems" were implemented in DSPs, because they could do that kind of processing so much faster and efficiently.
04-05-2019, 02:46 AM   #27
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Pentax is not alone. Look at "photonstophotos.net" to compare dynamic range of image sensors vs ISO for just about any camera. The Pentax K70, KP, and K1 II have a significant bump in the curve around ISO 640, older models do not. That tells me that amplifier/filter stages are being switched for different ISO settings. Similar bumps appear for the newer Sonys, Ricoh GR-III, Nikon D850, Z6, and Z7, but older Nikon models do not have the bump. It appears Pentax is switching in more gain than others to amplify low level signals at higher ISO settings, and that is what extends the apparent ISO sensitivity. I say apparent because it is pretty useless at the highest claimed ISO capability. This staged amplification seems to be a recent development that probably came from the sensor manufacturer, Sony, and that is why there is probably only one engineer at Pentax that really knows what is going on, and Ricoh won't let him talk to the public.
I found the photonstophotos,net site while searching to find a reason why there appeared to be less noise on my KP at ISO 640 vs. ISO 400. As far as I can tell from the curves, and my own shooting experience, there is virtually no difference in dynamic range and noise at ISO 100 or ISO 640, so 640 is my new floor for low light shooting.
04-05-2019, 05:23 AM   #28
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QuoteOriginally posted by tljensen Quote
Pentax is not alone.
Indeed. Fuji are also doing a lot of mystery work with their medium format GFX 50S, which shows a very steep jump from about ISO 1600, and that gain holding a long way onwards. 'Accelerator' gain bumps can show up anywhere today.

04-05-2019, 06:00 AM   #29
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QuoteOriginally posted by rawr Quote
Indeed. Fuji are also doing a lot of mystery work with their medium format GFX 50S, which shows a very steep jump from about ISO 1600, and that gain holding a long way onwards. 'Accelerator' gain bumps can show up anywhere today.
If you add the 645z curve, it will become apparent the Fuji added some "DR enhancement" from ISO1600 to ISO12800. Where Ricoh got is wrong with the K1 II is on the threshold. On the K1II , the threshold is at 640, same ISO level as on the KP. The accelerator kick on the K1 II should be around ISO 1250, 640 is too early for FF sensor. It looks like Ricoh did a straight reuse of the KP accelerator in the K1II. As a K1II user I can underexpose 1 stop if I want to get max sharpness.
04-05-2019, 06:16 AM   #30
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The GR III curve is also an interesting one.

A strong 'accelerator' boost kicks in even earlier than the KP. Ricoh seem to like this tech a lot.

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