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01-14-2011, 04:39 PM   #1
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K5: What do the quality levels correspond to?

The K5 (and apparently also the K7 and K-x) offer three quality settings for video (* to ***). I did some research but I could not find proper information regarding the compression these settings correspond to.

So far I only found another thread on the K-x (https://www.pentaxforums.com/forums/pentax-video-forum/84157-quality-levels-k-x.html) mentioning an instructive video on the three settings.

Does someone know where to get more information on this topic?

Thanks a lot!

01-14-2011, 08:48 PM   #2
hcc
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On the K-5, K-7, K-x, the quality level (or number of stars) is linked with the JPEG compression method. See a number of threads on the topic for the K-7 and K-x in this Forum.

With my K-7, I did a number of tests by changing systematically the number of Mp (14 Mp, 10 Mp, 6 Mp, 2 Mp) and for each number of Mp the number of stars from 4 stars down to 1 star. My tests were repeated systematically but I would not pretend to have performed scientific tests. After all tests, I looked at the resolutions and quality of the JPEGs.

At the end, I believe that the resolution (number of Mp) is more important than the number of stars. Hence 14 Mp is a better choice for the K-7.

For my K-7, I select as basic settings JPEG 14 Mp 2 stars. If I want more details, I select then RAW+ to have both RAW and JPEG files.

I hope that the comments will be of interest .....
01-16-2011, 05:03 PM - 1 Like   #3
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A quick test with the K-7 :

Still images :

File size kbytes

**** *** ** *
14M 11030 6219 3446 1602
10M 7492 4771 2494 1144
6M 4150 2965 1452 630
2M 1555 937 483 232

Size W H

14M 4672 3104
10M 3936 2624
6M 3072 2048
2M 1728 1152

Luminance Q

**** *** ** *
14M 100 96.95 91.86 74.16
10M 100 97.68 92.96 77.09
6M 98.32 97.29 91.86 74.16
2M 98.32 96.43 90.44 70.06

Chrominance Q

**** *** ** *
14M 100 96.99 91.90 74.24
10M 100 97.93 92.91 76.81
6M 98.83 97.51 91.90 74.24
2M 98.83 96.49 90.42 70.13

Still frames from video :


Still size W H

1.6M 1536 1024
0.9M 1280 720
0.3M 640 416

Luminance Q

*** ** *
1.6M 100 95.04 88.93
0.9M 98.32 96.06 91.86
0.3M 96.95 94.02 90.96

Chrominance Q

*** ** *
1.6M 100 94.91 88.89
0.9M 98.83 96.02 91.90
0.3M 96.99 93.93 90.96

All are 2:1 chroma subsampling


Photoshop equivalent

**** *** ** *
14M 12+ 11+ 10 4
10M 12+ 11+ 10 4
6M 12 11+ 10 4
2M 12 11+ 9 4

Photoshop uses 1:1 chroma subsampling at >6 quality.


Exact values will depend on the complexity of a particular image - your mileage may vary

Last edited by kh1234567890; 08-20-2011 at 02:45 AM.
01-17-2011, 01:08 PM   #4
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Thanks for the detailed answer! If I do find the time I'll try to compare this to own measurements on the K5. But I am pretty sure the values will be very close. For Jpeg I anyway don't think too much about compression and stick to the (****)-level. But for videos the pure size of the files is important considering that a many minutes of movie shooting are necessary to finally compose a few second film...

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