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sergiolov

JPG resolution loss

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Bob--

I ran some more tests today but on an in-focus subject. Ran the test twice, first on Auto exposure at 1/45 sec; second time at manually-set 1/60 sec:

 

First time--

card space taken by ten JPGs Fine: 33.1 MB

card space taken by ten JPGs Basic: 28.5 MB

 

Second time--

card space taken by ten JPGs Fine: 36 MB

card space taken by ten JPGs Basic: 25.7 MB

 

One peculiar thing:

The first time took 51 sec to write the DNGs (longest), 49 sec for the Fine JPGs, and 47 sec for the Basic JPGs.

Second time took 45 sec for the DNGs, 47 sec for the Fine JPGs, an 46 sec for the Basic JPGs.

I must have mis-timed the DNGs by 5 sec the first time, since DNGs generally write more quickly than JPGs.

 

Another inconsistency: Today's first try takes only 16% more card space for JPG Fine as compared to JPG Basic; second try takes 40% more space. Only the exposure was adjusted between the two runs.

 

Not making much headway.

Will continue to be interested in your results as well.

 

(For myself, I'm also not worried about write times, and not really about JPG output. But I have become curious since the topics have come up.)

 

It is beginning to look as if the M8's Fine compression isn't that much different from the Basic compression--and that goes back to Sergio's initial post.

 

--HC

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Isn't it the opposite? The ISO of the M8 needs to be raised to lighten its image to match the exposure from the D2X. So ISO 160 on the Nikon may require ISO 200 or so on the M8. (But an M8 only has full stops so you'd have to lower the ISO on the Nikon.)

 

I'm curious what kind of detail the Nikon would have at ISO 100.

 

While this test seems pretty tight for what you were trying to discover (raw vs. jpeg), maybe a test of both cameras at their lowest ISOs using f8 and varying the shutter speed until the histograms match would allow for maximum detail comparisons. (I'm not sure why the M8 image has so much less detail in the cable in the foreground - longer focal length, focused further back, lack of resolution?)

 

Plus I think one would need to set the Nikon lens a bit wider to match magnification.

 

Alan,

yes, the lens on m8 was 35mm while the lens of the d2x , the 17-35 2,8 was set at 32mm to match the field of view. Also, the 35mm was set to infinity, while the 17-35 was in autofocus mode, and might have gone to a little less than infinity. But the test was focused on jpeg comparison related to the quality of the raw in each camera, and not to compare the the results of the d2x vs the m8.

BTW, in general use, the resolution from the 2 cameras is practically similar, but the m8 wins in the noise department (1 1/2 stop) and clarity of color rendition. And has greater DR.

Sergio

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Bob--

I ran some more tests today but on an in-focus subject. Ran the test twice, first on Auto exposure at 1/45 sec; second time at manually-set 1/60 sec:

 

First time--

card space taken by ten JPGs Fine: 33.1 MB

card space taken by ten JPGs Basic: 28.5 MB

 

Second time--

card space taken by ten JPGs Fine: 36 MB

card space taken by ten JPGs Basic: 25.7 MB

 

One peculiar thing:

The first time took 51 sec to write the DNGs (longest), 49 sec for the Fine JPGs, and 47 sec for the Basic JPGs.

Second time took 45 sec for the DNGs, 47 sec for the Fine JPGs, an 46 sec for the Basic JPGs.

I must have mis-timed the DNGs by 5 sec the first time, since DNGs generally write more quickly than JPGs.

 

Another inconsistency: Today's first try takes only 16% more card space for JPG Fine as compared to JPG Basic; second try takes 40% more space. Only the exposure was adjusted between the two runs.

 

Not making much headway.

Will continue to be interested in your results as well.

 

(For myself, I'm also not worried about write times, and not really about JPG output. But I have become curious since the topics have come up.)

 

It is beginning to look as if the M8's Fine compression isn't that much different from the Basic compression--and that goes back to Sergio's initial post.

 

--HC

 

Good work Howard. Thanks.

I'll experiment a little in the weekend an report results.

Srgio

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Bob--

I ran some more tests today but on an in-focus subject.

Not making much headway.

Will continue to be interested in your results as well.

 

(For myself, I'm also not worried about write times, and not really about JPG output. But I have become curious since the topics have come up.)

 

It is beginning to look as if the M8's Fine compression isn't that much different from the Basic compression--and that goes back to Sergio's initial post.

 

--HC

Hi Howard,

The newpaper headlines today read "40 days of rain for San Antonio" and today was no different...

The compression ratios between Basic and Fine can't be too different and that to me is the "oops" in the programing. A native TIFF would be around 29MB, so the ratios are hovering around 1:10 to 1:6. A fine JPEG with half the compression of a basic would have made more sense. If they do rework the JPEG engine to recover detail, I hope they also alter the compression, too.

When you think of the processing steps going on (raw>DNG>jpeg vrs raw>jpeg), it just seems that for ideal light and exposure, the jpeg engine could have the advantage, being purpose built with fewer frills. As it is, it isn't really bad and good enough for snap shot/small print stuff. I have used it in situations where I should have put the camera away, and got some interesting results, including a shot that my wife thinks is the best picture that I have ever taken of her in the 24 years of marriage....fine detail isn't always desired by the mature:rolleyes:

Bob

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Hi Howard,

I had a brief moment os sunshine and got the gear out and the sun went away, before I set up. It wasn't raining so I went ahead. I shot the following image, for "detail count" in Fine and Basic. ISO160 settings standard except the EV at -1/3. File sizes are Fine = 8.40MB & Basic = 5.88MB. I didn't measure write times, but they seemed the same to me. Lens was the 28mm Elmarit Asph.

I then ran an absolute difference to see any compression differences (artifacts?). I had to brighten it to see anything and then made a 100% crop. The brightness in the original AbDiff would indicate the severity/magnitude, so there are differences, but not as sever as indicated.

Anyway, a little fun on another rainy day.

Bob

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Bob--

Lovely work! For "Absolute difference" (what a great idea!) what did you do? Overlay the two and set PS color mode to "difference"?

 

I also spent too much of a rainy day running down my earlier errors by reshooting a fair amount. My problem above figuring file sizes was that I forgot to press "Set" after choosing a new JPG compression, so ended up with the same as previous.

Boy, am I embarrassed!

 

Anyway, I found in three different tests today that the M8's JPG Basic setting writes a file about 1/3 smaller than JPG Fine (though that is quite variable). (Your file sizes are consistent with that, showing a 30% difference.)

 

I also re-ran the write tests: Making the same shot ten times and waiting till the buffer empties takes 55 sec for JPG Fine, and 46 sec for JPG Basic. So it will likely take longer to write a higher-quality file if we get one.

 

 

I ran comparisons also with a D200. The Nikon's files came out about 1/3 larger for JPG Fine in 'optimal quality' mode than the M8's. (The Nikon's JPG Fine files in 'size priority' mode came out almost identical to the M8's JPG Fine.)

 

In other words--and judging only from file size--on my D200 as well as Sergio's D2x, the Nikon's highest quality JPGs definitely seem to offer more data than those of the M8.

 

--HC

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Hi Howard,

I use Picrure Window Pro and it has an option in the composite tool for it. I think PS has it, too, maybe in the layer flattening tool. One interesting thing is that I downloaded the images from the card using Irfanview and saved them at 100% (0% compression) JPEGs The Fine version of 8.4MB saved at 9.35MB and the Basic version of 5.88MB saved at 8.81MB. I'm not sure what is going on, but maybe this is why I haven't seen any compression artifacts described and shown by others, even with standard sharpening. One of these days I'll experiment with saving as a TIFF (with Irfanview) and do an absolute difference with a Fine JPEG. The absolute difference composit does let me know where to look for nasties. At my age I need all the guidance I can get.

Bob

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