«

Roger N Clarke found in a very interesting test
that the 10D clipped one stop lower when saving
as JPEG compared to saving as RAW. This will
zap all the white parts in the RAW original.

http://clarkvision.com/imagedetail/dynamicrange

This is a rather peculiar behaviour, not easily
to motivate. Now, Roger may be wrong of course.

Is it possible that someone can make the following
test. Take a picture, with a small white object, using
several manual exposures, both with RAW and JPEG.

Then, comparing the JPEG to a 16 bit TIF (extracted
from the RAW) to see whether the small white object
contains details at the same exposures or the white
object loses the details at a lesser exposure.


/Roland

>From: Roland Karlsson

>Roger N Clarke found in a very interesting test
>that the 10D clipped one stop lower when saving
>as JPEG compared to saving as RAW. This will
>zap all the white parts in the RAW original.

Roger's test is a bit complicated, to say the least. I have no idea what that
graph of plots is supposed to represent. However, the comparison is really
between 8-bit files and 16-bit files, not JPG vs. TIF.... I think.
Or perhaps Roger is attempting to show the advantages of shooting in RAW mode.
I'll let him explain it.

Roland Karlsson wrote:

> Roger N Clarke found in a very interesting test
> that the 10D clipped one stop lower when saving
> as JPEG compared to saving as RAW. This will
> zap all the white parts in the RAW original.
>
> http://clarkvision.com/imagedetail/dynamicrange
>
> This is a rather peculiar behaviour, not easily
> to motivate. Now, Roger may be wrong of course.
>
> Is it possible that someone can make the following
> test. Take a picture, with a small white object, using
> several manual exposures, both with RAW and JPEG.
>
> Then, comparing the JPEG to a 16 bit TIF (extracted
> from the RAW) to see whether the small white object
> contains details at the same exposures or the white
> object loses the details at a lesser exposure.
>
>
> /Roland
------------------
Quite apart from this technical explanation... I have found from day one
that shooting in .jpg mode when there are bright highlights will result
in the complete loss of detail in those highlights.

I originally put it down to multi-spot metering but changing that to
centre spot only moderately altered the effect. I still shoot .jpg mode
indoors, under flash with great success but no more will I shoot in
sunlight any other method than RAW.

oddly enough, the small preview image often shows the detail missing
later in the .jpg file!

Ryadia.

In message <>,
(Annika1980) wrote:

>>From: Roland Karlsson
>
>>Roger N Clarke found in a very interesting test
>>that the 10D clipped one stop lower when saving
>>as JPEG compared to saving as RAW. This will
>>zap all the white parts in the RAW original.
>
>Roger's test is a bit complicated, to say the least. I have no idea what that
>graph of plots is supposed to represent. However, the comparison is really
>between 8-bit files and 16-bit files, not JPG vs. TIF.... I think.
>Or perhaps Roger is attempting to show the advantages of shooting in RAW mode.
>I'll let him explain it.

Dynamic range at the highlight end has nothing to do with 8-bit vs 16
bit. That's just a matter of level granularity. On the dark end, the
higher bit depth will allow more distinguishable shadows. It has
nothing to do with TIFF vs JPEG, either, as the linear TIFF is simply a
TIFF that has no gamma correction. A 16 bit TIFF can be gamma-corrected
to, as are the TIFFs made by any RAW converter, and they may have the
same clipping point as a camera JPEG.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><

In message <>,
Ryadia <> wrote:

>oddly enough, the small preview image often shows the detail missing
>later in the .jpg file!

That is impossible. You are viewing the JPEG in the review. The 10D
never renders from RAW to the screen; it renders to JPEG and then to the
screen.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><

Roland Karlsson wrote:
> Roger N Clarke found in a very interesting test
> that the 10D clipped one stop lower when saving
> as JPEG compared to saving as RAW. This will
> zap all the white parts in the RAW original.
>
> http://clarkvision.com/imagedetail/dynamicrange
>
> This is a rather peculiar behaviour, not easily
> to motivate. Now, Roger may be wrong of course.
>
> Is it possible that someone can make the following
> test. Take a picture, with a small white object, using
> several manual exposures, both with RAW and JPEG.
>
> Then, comparing the JPEG to a 16 bit TIF (extracted
> from the RAW) to see whether the small white object
> contains details at the same exposures or the white
> object loses the details at a lesser exposure.
>
>
> /Roland

Hi guys.
The test I did was raw plus jpeg on the same image for the
canon 10D. The jpeg is clipped and shows less highlights
than the raw (16-bit tiff converted). This is seen in Figure 4
on the page: the highlights on the dog are clipped.

I often see this problem with the 10D and 8-bit jpegs
versus 16-bit raw (really 12 bit). In particular
I have had this problem a lot imaging white birds, and often
underexpose 1 to 2 stops to prevent clipping. I like to avoid
raw because I can get so many more images on a card.
My new 1D Mark II seems to meter better in this regard, but the
problem is still there in the jpegs versus raw. The 1DII seems
to meter better if there is a small bright area in the scene
and adjusts exposures better.

Roger

In article <Xns9558E1AC07495klotjohan@130.133.1.4>,
Roland Karlsson <> wrote:

> Roger N Clarke found in a very interesting test
> that the 10D clipped one stop lower when saving
> as JPEG compared to saving as RAW. This will
> zap all the white parts in the RAW original.
>
> http://clarkvision.com/imagedetail/dynamicrange
>
> This is a rather peculiar behaviour, not easily
> to motivate. Now, Roger may be wrong of course.
>
> Is it possible that someone can make the following
> test. Take a picture, with a small white object, using
> several manual exposures, both with RAW and JPEG.
>
> Then, comparing the JPEG to a 16 bit TIF (extracted
> from the RAW) to see whether the small white object
> contains details at the same exposures or the white
> object loses the details at a lesser exposure.
>
>
> /Roland

The rendering of the JPEG is based on the camera's image adjustment
parameters. RAW is a sensor dump with the camera's image adjustment
parameters included for future rendering hints. JPEG is processed, RAW
is not.

It's important that you keep your camera's image parameters tuned for
your shooting environment if you're going to use JPEG mode. The wrong
parameters will cause visual quality to be lost during the conversion to
24 bit RGB. This is true of any camera.

In article <>,
Roger N. Clark (change username to rnclark) <> wrote:

>Hi guys.
>The test I did was raw plus jpeg on the same image for the
>canon 10D. The jpeg is clipped and shows less highlights
>than the raw (16-bit tiff converted). This is seen in Figure 4
>on the page: the highlights on the dog are clipped.
>
>I often see this problem with the 10D and 8-bit jpegs
>versus 16-bit raw (really 12 bit).

It's common practice when doing an automated levels adjustment (as will
happen during JPEG conversion in the camera) to clip the histogram slightly.
Photoshop does it in auto levels/auto contrast, for example, and the default
for Photoshop CS's raw convertor is to clip the shadows slightly.

If you want a quickly usable image, this is actually quite sensible. If you
produce a JPEG that holds the entire histogram, it will typically look
"muddy" without some manual intervention.

Having said that, it is perhaps fair to say that Canon has traditionally
been a bit aggressive about where they clip the histogram in their DSLRs.

Ultimately, however, we're in "nothing to see here, move along" territory.
If you want full control over how the levels are set in your image, shoot
RAW and don't let any "auto-levels/contrast" operations anywhere near it,
regardless of whether they happen in-camera, or in Photoshop.

The preview image I write about is the preview in the .jpg file, not the one
you refer to.

Ryadia
----------------------
<> wrote in message
news:...
> In message <>,
> Ryadia <> wrote:
>
> >oddly enough, the small preview image often shows the detail missing
> >later in the .jpg file!
>
> That is impossible. You are viewing the JPEG in the review. The 10D
> never renders from RAW to the screen; it renders to JPEG and then to the
> screen.
> --
>
> <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
> John P Sheehy <>
> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><

In message <>,
"Ryadia" <> wrote:

>The preview image I write about is the preview in the .jpg file, not the one
>you refer to.

I now have absolutely no idea what you're talking about.

><> wrote in message
>news:.. .
>> In message <>,
>> Ryadia <> wrote:
>>
>> >oddly enough, the small preview image often shows the detail missing
>> >later in the .jpg file!
>>
>> That is impossible. You are viewing the JPEG in the review. The 10D
>> never renders from RAW to the screen; it renders to JPEG and then to the
>> screen.

--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><