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JPEG + DNG, who's making the JPEG?

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Offline davecool

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JPEG + DNG, who's making the JPEG?
« on: 05 / September / 2010, 07:24:19 »
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I have my SX20 set to save both JPEGs and DNGs. CHDK is creating the DNG files, but is CHDK also developing and compressing the JPEGs? Or is the original firmware still doing that task? Thanks!
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Offline fudgey

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Re: JPEG + DNG, who's making the JPEG?
« Reply #1 on: 05 / September / 2010, 07:34:26 »
Canon does your JPEGs. The ARM CPU CHDK runs on is too slow to tackle that task fast enough.
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Offline davecool

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Re: JPEG + DNG, who's making the JPEG?
« Reply #2 on: 05 / September / 2010, 12:41:40 »
Excellent, that's actually the answer I was hoping for. So, is that still the case when I override the JPEG quality setting? Ie, my camera doesn't support "super fine" but I can override it with CHDK. Does that mean that the Canon firmware _does_ support that JPEG mode and just isn't exposing it through the interface?
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Offline fudgey

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Re: JPEG + DNG, who's making the JPEG?
« Reply #3 on: 05 / September / 2010, 13:30:50 »
Quote from: davecool on 05 / September / 2010, 12:41:40
Excellent, that's actually the answer I was hoping for. So, is that still the case when I override the JPEG quality setting? Ie, my camera doesn't support "super fine" but I can override it with CHDK. Does that mean that the Canon firmware _does_ support that JPEG mode and just isn't exposing it through the interface?

Yes, it's still the Digic's DSP section or a hardware JPEG codec doing all the work even if you override it. It's not about what the firmware supports or not, it's what the codec supports and with which parameters Canon has chosen to use it and whether CHDK can change that. If CHDK for your camera has a JPEG quality override that produces larger JPEG files with more detail, the codec obviously supports a lighter compression setting than what Canon firmware will let you use.
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Offline davecool

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Re: JPEG + DNG, who's making the JPEG?
« Reply #4 on: 05 / September / 2010, 15:19:24 »
Wonderful, I understand now. Thanks!
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