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01-08-2016, 02:04 PM   #1
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645z jpeg's are like raw files now?

I just noticed that I can process 645z's in-camera jpgs exactly like raw pef files in Pentax Digital Camera Utility software.. all the tools for raw can be used for jpg's like changing color modes, exposure, white-balance, etc. Also means I can tweak 645z's HDR jpg's just like a raw file, which is huge especially since I use this feature alot.. just got me thinking why I would want to keep a raw fie around? anyone else curious about that?

01-08-2016, 02:09 PM - 1 Like   #2
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QuoteOriginally posted by acarlay Quote
I just noticed that I can process 645z's in-camera jpgs exactly like raw pef files in Pentax Digital Camera Utility software.. all the tools for raw can be used for jpg's like changing color modes, exposure, white-balance, etc. Also means I can tweak 645z's HDR jpg's just like a raw file, which is huge especially since I use this feature alot.. just got me thinking why I would want to keep a raw fie around? anyone else curious about that?
Jpegs are compressed files with lots of data tossed out. Everytime you edit and save, you are tossing out even more data. YOU might not be able to see the difference, buts its there and its real. RAW editing doesn't effect the original file, includes tons more data to edit and doesn't toss out anything.
01-08-2016, 02:25 PM   #3
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so everytime you edit and save a jpeg, the jpeg gets compressed again? i understand from raw to jpeg it will get compressed and lose some data, but jpeg to jpeg?
01-08-2016, 02:25 PM   #4
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QuoteOriginally posted by acarlay Quote
I just noticed that I can process 645z's in-camera jpgs exactly like raw pef files in Pentax Digital Camera Utility software.. all the tools for raw can be used for jpg's like changing color modes, exposure, white-balance, etc. Also means I can tweak 645z's HDR jpg's just like a raw file, which is huge especially since I use this feature alot.. just got me thinking why I would want to keep a raw fie around? anyone else curious about that?
The raw file contains way more data than a JPEG. Think of a JPEG as the result of RAW processing.

When shooting in raw mode, you can use the Pentax desktop software to create a JPEG identical to the one the camera would have created in JPEG mode. The opposite isn't true.

Sounds to me like you may have been shooting in RAW+ or something, since in-camera development also only applies to raw files.


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01-08-2016, 02:27 PM - 1 Like   #5
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QuoteOriginally posted by acarlay Quote
so everytime you edit and save a jpeg, the jpeg gets compressed again? i understand from raw to jpeg it will get compressed and lose some data, but jpeg to jpeg?
Yes it will lose data, since JPEG is a lossy format.

If you develop a raw file 100 times, the resulting JPEGs will all have the same quality. However, if you edit and save a JPEG file 100 times, you'll get something much, much worse.

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01-08-2016, 02:29 PM   #6
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QuoteOriginally posted by Adam Quote
The raw file contains way more data than a JPEG. Think of a JPEG as the result of RAW processing.

When shooting in raw mode, you can use the Pentax desktop software to create a JPEG identical to the one the camera would have created in JPEG mode. The opposite isn't true.

Sounds to me like you may have been shooting in RAW+ or something, since in-camera development also only applies to raw files.
Adam you can edit a 645z jpg with Pentax's desktop software and have all the features available to you.. it doesn't only apply to raw files.
01-08-2016, 02:50 PM   #7
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QuoteOriginally posted by acarlay Quote
Adam you can edit a 645z jpg with Pentax's desktop software and have all the features available to you.. it doesn't only apply to raw files.
That still doesn't free you from the loss of data that results from decoding and re-encoding a JPEG file.
01-08-2016, 03:40 PM   #8
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QuoteOriginally posted by Adam Quote
Yes it will lose data, since JPEG is a lossy format.

If you develop a raw file 100 times, the resulting JPEGs will all have the same quality. However, if you edit and save a JPEG file 100 times, you'll get something much, much worse.
You actually will not get something much much worse. It will certainly be worse than a jpeg from a raw file, but not any worse than shooting jpeg from the camera. The way jpeg compression works, you can save a jpeg a thousand times and it won't reduce the quality of the jpeg so as long as you keep the same quality setting.

01-08-2016, 03:43 PM - 1 Like   #9
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QuoteOriginally posted by acarlay Quote
Adam you can edit a 645z jpg with Pentax's desktop software and have all the features available to you.. it doesn't only apply to raw files.
This is quite true, almost any processing software (I use Lightroom for example) will handle RAW or jpeg without any issues, often without you even noticing what format you are using. But as already noted the jpeg has already been derived from the RAW in camera and a lot of info was tossed out. So first you can develop the jpeg and you have all the tools, but you no longer have all the data so your range of latitude for developing is reduced. And second if you develop a jpeg and re-save you toss out even more info.

In practical use, this is not a big issue. If you develop a jpeg and save you lose some info but not a lot. Where it gets bad is if you edit and save multiple times, then it gets ugly. But if you are making your edits, saving and done then sure it's no big deal.

Working from the RAW will always be a better workflow though, IMHO. I never touch a jpeg. Basically I consider a jpeg exactly the same as a print, you don't edit prints, you don't edit jpegs.
01-08-2016, 03:43 PM   #10
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QuoteOriginally posted by acarlay Quote
Adam you can edit a 645z jpg with Pentax's desktop software and have all the features available to you.. it doesn't only apply to raw files.
I tested recently some JPEGs (from the K7) in PDCU 4.40, and I found that the Auto lens corrections (Distortion, Marginal Luminance, Chromatic etc) were all greyed out .... it was possible to make the manual adjustments though. I assumed that the metadata for auto corrections was not saved in the JPEG (or there was nowhere for it to be saved in the JPEG). Is this the same with the 645z jpegs?
01-08-2016, 03:50 PM   #11
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QuoteOriginally posted by Dipsoid Quote
You actually will not get something much much worse. It will certainly be worse than a jpeg from a raw file, but not any worse than shooting jpeg from the camera. The way jpeg compression works, you can save a jpeg a thousand times and it won't reduce the quality of the jpeg so as long as you keep the same quality setting.
This is bad info and not true. Each save re-compresses the image, however minute. Each save degrades the image.

Saving JPEG Photos Hundreds of Times
01-08-2016, 03:57 PM - 1 Like   #12
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QuoteOriginally posted by enoeske Quote
This is bad info and not true. Each save re-compresses the image, however minute. Each save degrades the image.

Saving JPEG Photos Hundreds of Times
No, it does not, as long as you keep the same quality setting.

01-08-2016, 04:32 PM   #13
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Correct..
01-08-2016, 05:08 PM   #14
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yes the quaity setting makes sense.. thank you.

anyway on a similar note.. there's a feature on 645z's HDR mode that allows you to save the 3 image captures into one RAW pef file as long as you don't set the output to Raw+.. you can set HDR mode either to RAW or jpeg.. and in addition if you set it to jpeg from HDR mode the 645z can create a RAW file on the fly, if you choose to after shooting a frame, which is so cool.. it's called RAW (HDR).. anyway i'm bringing this up because a RAW(HDR) file is very huge -- it can be up to 200mb large and will eat up so much space.. that's why this jpg thing is kinda exciting for me.. so i lose some data from the conversion but I'm stil able to change color modes, etc. which I thought I couldn't do with jpegs..
01-08-2016, 05:20 PM   #15
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QuoteOriginally posted by Dipsoid Quote
No, it does not, as long as you keep the same quality setting.
I'm not from the 645Z camp, but I was reading this thread and found that statement fascinating. I shoot in RAW, but I have many JPG files from the years before I even knew that shooting in RAW was the way to go (for me, at least). Is it actually the case that if I take an existing JPG file into Photoshop, edit it, and save with the highest possible quality, it won't have *any* additional degradation and artefacts? Also, if I have a JPG that was created by a different piece of software (or in camera firmware), and load / edit / save in best quality in Photoshop, there will literally be *no* degradation whatsoever? That would be a really useful to know. Thanks in advance.
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