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12-18-2010, 11:11 AM   #1
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K-7 JPEG Quality four stars vs. three stars

While I know RAW is the best way to shoot, I don't have the appropriate software to convert RAW files to JPEGs or TIFFs quickly enough to use RAW all the time. I'm trying to get the maximum out of my camera using JPEGs.

On the first page of my menu I recently switched the JPEG quality selection to 4 stars from the default 3 star setting on my K-7. I am not sure if I really see any difference except the size of my pictures files has jumped dramatically.

Is anyone aware of any formal study about how much difference there is between the two setting? I have a two 16 Gig cards and lots of hard drive space so I have the space to shoot at the higher setting, but don't know what I'm really gaining in practical terms by shooting at the four star setting.

I would appreciate others thoughts or professional test results if anyone knows about them.



12-18-2010, 11:53 AM   #2
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Since it's a lossy format, saving at the highest quality setting might be preferable if you might be doing any photoshopping etc on the image, if I'm not mistaken. Also, and perhaps this is entirely insignificant, I wonder if the lower quality setting, which I presume uses more compression, might make saving the JPEG slightly slower? Or perhaps the lower quality setting is quicker?? ... anyway, since you have the space, why not shoot both RAW and JPEG; it might be nice to have those RAW files further on down the road.

I shoot RAW plus JPEGs saved at only 2 megapixels, quality 3, just because I want them if I need to quickly email someone a snapshot from work, for example, where I don't have conversion software.
12-18-2010, 02:53 PM - 1 Like   #3
hcc
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PentaxRev,
Your message contains many queries/questions.

* To view the RAW files, use Pentax Digital Camera Utility (PDCU). In PDCU, you can convert any RAW photo into JPEG.

* PDCU is free with your K-7 and it will allow some simple, easy post-processing (PP).

* If you wish to save the highest resolution file and get some smaller files to manipulate at the same time, the RAW+ is the best option.

* I shoot JPEG only. I tried all JPEG file sizes and star resolutions for several test cases.After many trials:
(a) I chose 14 Mp 2 stars. The 14 Mp gives me the full resolution of the sensor while the 2 stars [**] yield a reasonable file size. Like you I have a 16 Gb card and I do not want to fill it up when I travel.

(b) at 14 and 6 Mp, I see little difference, if none, between 3 stars and 4 stars JPEG.


I hope that the comments will help....
12-18-2010, 05:48 PM   #4
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Dear HCC,

Thanks for your reply. I know the Pentax software will do the conversion from RAW to JPEG. I do have that software, but I have been using Photoshop Elements 7. It's a fine program, but when I shoot RAW I have to convert each pic separately to JPEG and it takes longer than I want to spend. Perhaps I need to check out the Pentax program to see if it might be more effecient in RAW.

I used the Pentax software that came with my K10D but haven't even opened the K-7's software. The previous software didn't seem all that user friendly, but perhaps I just need to spend some time working with it. I think I'll be getting Elements 9 for Christmas and perhaps it will have a more effecient means of converting RAW to JPEG or TIF.

I appreciate your input.

12-18-2010, 06:02 PM   #5
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QuoteQuote:
I'm trying to get the maximum out of my camera using JPEGs.
Maybe you're working at this from the wrong direction.
What do you want as an end result? i.e. How will you be using these JPEGs?

If you're mainly keeping for memories, posting to email and websites and not doing any significant post processing, ** or *** jpegs are just fine.

If you plan to make multiple or complex edits, starting with low quality JPGs will reduce your ability to keep a high quality image throughout your process. You should think about keeping **** jpegs at the least, or moving to RAW.
12-18-2010, 06:11 PM - 1 Like   #6
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QuoteOriginally posted by PentaxRev Quote
when I shoot RAW I have to convert each pic separately

In PDCU you can select all and convert all at once with the same settings - unattended while you go out to dinner. Tweak the ones that need it.

In Elements, go File > Process Multiple Images, and it will ask for the directory to do, among other things.
12-18-2010, 06:53 PM   #7
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QuoteOriginally posted by SpecialK Quote
In PDCU you can select all and convert all at once with the same settings - unattended while you go out to dinner. Tweak the ones that need it.

In Elements, go File > Process Multiple Images, and it will ask for the directory to do, among other things.
Thanks for the great information. It's a case of not understanding the full capabilities of what I already have.

I'm looking forward to shooting RAW and then converting the files.

I'm excited!
12-19-2010, 05:07 AM   #8
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QuoteOriginally posted by PentaxRev Quote
Is anyone aware of any formal study about how much difference there is between the two setting?
You could always use ImpulseAdventure - JPEGsnoop - JPEG Decoding Utility to see what the difference between the two compressions actually is.

12-20-2010, 04:17 PM   #9
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QuoteOriginally posted by kh1234567890 Quote
You could always use ImpulseAdventure - JPEGsnoop - JPEG Decoding Utility to see what the difference between the two compressions actually is.
i like to try this program , but it seem just the number that's come out... how to use it ?
12-21-2010, 03:22 AM   #10
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QuoteOriginally posted by ewig Quote
i like to try this program , but it seem just the number that's come out... how to use it ?
Read ImpulseAdventure - JPEG Quality Comparison

In the first instance the things to look for are the luminance and chrominance quality factors (nearer to 100 is better) and the chroma subsampling (1x1 best 2x2 worst).

For example :

*** Marker: DQT (xFFDB) ***
Define a Quantization Table.
OFFSET: 0x00005678
Table length = 132
----
Precision=8 bits
Destination ID=0 (Luminance)
DQT, Row #0: 1 1 1 1 1 2 3 4
DQT, Row #1: 1 1 1 1 2 3 4 3
DQT, Row #2: 1 1 1 1 2 3 4 3
DQT, Row #3: 1 1 1 2 3 5 5 4
DQT, Row #4: 1 1 2 3 4 7 6 5
DQT, Row #5: 1 2 3 4 5 6 7 6
DQT, Row #6: 3 4 5 5 6 7 7 6
DQT, Row #7: 4 6 6 6 7 6 6 6
Approx quality factor = 96.95 (scaling=6.11 variance=1.09)
----
Precision=8 bits
Destination ID=1 (Chrominance)
DQT, Row #0: 1 1 1 3 6 6 6 6
DQT, Row #1: 1 1 2 4 6 6 6 6
DQT, Row #2: 1 2 3 6 6 6 6 6
DQT, Row #3: 3 4 6 6 6 6 6 6
DQT, Row #4: 6 6 6 6 6 6 6 6
DQT, Row #5: 6 6 6 6 6 6 6 6
DQT, Row #6: 6 6 6 6 6 6 6 6
DQT, Row #7: 6 6 6 6 6 6 6 6
Approx quality factor = 96.99 (scaling=6.01 variance=0.24)

*** Marker: SOF0 (Baseline DCT) (xFFC0) ***
OFFSET: 0x000058A2
Frame header length = 17
Precision = 8
Number of Lines = 3104
Samples per Line = 4672
Image Size = 4672 x 3104
Raw Image Orientation = Landscape
Number of Img components = 3
Component[1]: ID=0x01, Samp Fac=0x21 (Subsamp 1 x 1), Quant Tbl Sel=0x00 (Lum: Y)
Component[2]: ID=0x02, Samp Fac=0x11 (Subsamp 2 x 1), Quant Tbl Sel=0x01 (Chrom: Cb)
Component[3]: ID=0x03, Samp Fac=0x11 (Subsamp 2 x 1), Quant Tbl Sel=0x01 (Chrom: Cr)

12-21-2010, 03:38 AM   #11
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QuoteOriginally posted by PentaxRev Quote
While I know RAW is the best way to shoot, I don't have the appropriate software to convert RAW files to JPEGs or TIFFs quickly enough to use RAW all the time.

You can download Picassa for free, takes about 90 seconds and then you have a raw viewer as well as a way to convert from raw to jpeg. Simple as that. If you want something (also free and easily downloaded) try "raw therapee" whch gives you way more options to edit with as well as saving to jpeg, tiff, etc.

What happened the silkypix software that came with the camera body? Know what batch processing is?

Jason
12-21-2010, 06:21 AM   #12
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QuoteOriginally posted by SpecialK Quote
In PDCU you can select all and convert all at once with the same settings - unattended while you go out to dinner. Tweak the ones that need it.

In Elements, go File > Process Multiple Images, and it will ask for the directory to do, among other things.
Either Elements 7 doesn't offer this option, or I was in the wrong place when I attempted to do it. There was no "process multiple images" option under file.

So I moved the RAW files to my external hard drive as TIFs. However, when I opened them they had grown... a lot. I thought RAW was the most space hungry format, but the pictures went from about 11.4 MB to 43 MB. Was I doing something wrong or are TIF files simply much larger than RAW files?
12-21-2010, 09:41 AM   #13
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TIFFs are really, really big.

I did that a few times and ended up, IIRC, about 50 MB.

So I don't do that now ....
12-22-2010, 05:29 AM   #14
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What I've finally worked out is shooting RAW (I can tell the difference) and then exporting the files to a JPEG format on my external hard drive. I think it's a system that is going to work fine. Everyone, thanks for your good ideas and support.

Asking questions and getting answers like so many of you gave me are small steps in the process of becoming a better photographer.
04-02-2016, 07:49 AM   #15
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QuoteOriginally posted by amoringello Quote
Maybe you're working at this from the wrong direction.
What do you want as an end result? i.e. How will you be using these JPEGs?

If you're mainly keeping for memories, posting to email and websites and not doing any significant post processing, ** or *** jpegs are just fine.

If you plan to make multiple or complex edits, starting with low quality JPGs will reduce your ability to keep a high quality image throughout your process. You should think about keeping **** jpegs at the least, or moving to RAW.
A lot of software that edits pictures these days is non destructive. So it won't damage the original file. If you edit it in Photoshop, and save it as a JPEG every time. Then of course it will reduce the quality every time you save it as a JPEG. Adobe light room and photos for the Mac, both are nondestructive editors. So they will not ruin the original JPEG copy even if you put in tons of edits.
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