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Why is Raw better than jpeg

 
 
ransley
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      08-06-2010
I use the T1i, dpreview gives a higher rating to Jpeg over Raw. I
believe its because Jpegs settings are optimised by Canon very well.
For my jpegs they come out very good. Is Raw recomended because jpeg
looses quality every time you open and close it? Is the difference
noticable by opening and closing it say for example 5 times printed at
5x7 or 8x11? Does the loss on jpeg only occur if you completely close
the photo? What are other benefits of Raw to make it worth the extra
hassle of complete editing. I am happy shooting jpeg, I am working
with 5 shot Photomatrix hdr and have done both Raw and jpeg [I think
Photomatrix loaded the jpeg] I am fully happy with the results but
jpeg is so much easier. I think for special photos made and composed
Raw may be optimal , but its time very consuming.
 
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Martin Brown
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      08-06-2010
On 06/08/2010 13:02, ransley wrote:
> I use the T1i, dpreview gives a higher rating to Jpeg over Raw. I
> believe its because Jpegs settings are optimised by Canon very well.
> For my jpegs they come out very good. Is Raw recomended because jpeg
> looses quality every time you open and close it? Is the difference
> noticable by opening and closing it say for example 5 times printed at
> 5x7 or 8x11? Does the loss on jpeg only occur if you completely close
> the photo?


This is a FAQ and dealt with in the JPEG FAQ. See Q10 of

http://www.faqs.org/faqs/jpeg-faq/part1/

Opening and closing a JPEG file doesn't alter it at all unless you Save
the file again as a JPEG *and* overwrite the original file. If you treat
your original JPEGs are readonly then there is no problem at all.

The level of degradation with successive saves is not huge provided that
you work at a fixed quality level. But it is ever present. This means
that in a workflow you want to keep work in progress saved in a lossless
format (typically one native to the application you are using that will
preserve layers and masks).

> What are other benefits of Raw to make it worth the extra
> hassle of complete editing. I am happy shooting jpeg, I am working
> with 5 shot Photomatrix hdr and have done both Raw and jpeg [I think
> Photomatrix loaded the jpeg] I am fully happy with the results but
> jpeg is so much easier. I think for special photos made and composed
> Raw may be optimal , but its time very consuming.


Raw gives you more freedom afterwards to rescue dynamic range and adjust
colour balance. This can be important if you know that the image will
contain black velvet in shadow and a white bridal dress in sunlight. And
there is little chance of retaning it if the exposure is even slightly
off. It is hard for the in camera auto adjust and save as JPEG to get
both exactly right simultaneously and a risk if you let it.

Most of the time in camera JPEG encoding is fine - ie good enough.
(some makers high quality JPEG encoding is better than others)

Regards,
Martin Brown

 
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ransley
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Posts: n/a
 
      08-06-2010
On Aug 6, 7:21*am, Martin Brown <|||(E-Mail Removed)>
wrote:
> On 06/08/2010 13:02, ransley wrote:
>
> > I use the T1i, dpreview gives a higher rating to Jpeg over Raw. I
> > believe its because Jpegs settings are optimised by Canon very well.
> > For my jpegs they come out very good. Is Raw recomended *because jpeg
> > looses quality every time you open and close it? Is the difference
> > noticable by opening and closing it say for example 5 times printed at
> > 5x7 or 8x11? Does the loss on jpeg only occur if you completely close
> > the photo?

>
> This is a FAQ and dealt with in the JPEG FAQ. See Q10 of
>
> http://www.faqs.org/faqs/jpeg-faq/part1/
>
> Opening and closing a JPEG file doesn't alter it at all unless you Save
> the file again as a JPEG *and* overwrite the original file. If you treat
> your original JPEGs are readonly then there is no problem at all.
>
> The level of degradation with successive saves is not huge provided that
> you work at a fixed quality level. But it is ever present. This means
> that in a workflow you want to keep work in progress saved in a lossless
> format (typically one native to the application you are using that will
> preserve layers and masks).
>
> > What are other benefits of Raw to make it worth the extra
> > hassle of complete editing. I am happy shooting jpeg, I am working
> > with 5 shot Photomatrix hdr and have done both Raw and jpeg [I think
> > Photomatrix loaded the jpeg] *I am fully happy with the results but
> > jpeg is so much easier. I think for special photos made and composed
> > Raw may be optimal , but its time very consuming.

>
> Raw gives you more freedom afterwards to rescue dynamic range and adjust
> colour balance. This can be important if you know that the image will
> contain black velvet in shadow and a white bridal dress in sunlight. And
> there is little chance of retaning it if the exposure is even slightly
> off. It is hard for the in camera auto adjust and save as JPEG to get
> both exactly right simultaneously and a risk if you let it.
>
> Most of the time in camera JPEG encoding is fine - ie good enough.
> (some makers high quality JPEG encoding is better than others)
>
> Regards,
> Martin Brown


I use Adobe and just save as it prompts me, is that the proper way? I
wonder since Canons jpeg is optimised if I am not going backwards with
Raw and missing what they have put major effort into perfecting. How
is dynamic range improved? Color balance controls in editing are the
same, how is Raw better?
 
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Ofnuts
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Posts: n/a
 
      08-06-2010
On 06/08/2010 14:02, ransley wrote:
> I use the T1i, dpreview gives a higher rating to Jpeg over Raw. I
> believe its because Jpegs settings are optimised by Canon very well.
> For my jpegs they come out very good. Is Raw recomended because jpeg
> looses quality every time you open and close it?


No... RAW is recommended because JPEG can only code 8 bits per "channel"
(*). In a camera with significantly more than 8 bits per channel (**)
going to JPEG requires to discard some information, which cannot be
recoverdd later. RAW allows these choices to be made later (and pick up
among them the best choice for a specific photo).

> Is the difference
> noticable by opening and closing it say for example 5 times printed at
> 5x7 or 8x11?


JPEG loss only happen when you save the file. If you only open the file
for printing nothing happens to the orginal file.

> Does the loss on jpeg only occur if you completely close
> the photo?


"Close", no. "Save", yes, to some extent. This is why applications that
re-save the picture behind your back should be taken out and shot (this
is what happens with Windows Picture and Fax viewer when you rotate the
photo). But for the "quality" setting of most photos, this is very minor
and you won't notice anything un,les you edit and save the image ober a
dozen times. But you can completely avoid this by saving the
intermediate versions in a lossless format (TIFF, for instance) or the
native format of you picture editor (this will save layers, selections
and whatever) and only export to JPEG the final result.

> What are other benefits of Raw to make it worth the extra
> hassle of complete editing.


Showing off

> I am happy shooting jpeg, I am working
> with 5 shot Photomatrix hdr and have done both Raw and jpeg [I think
> Photomatrix loaded the jpeg] I am fully happy with the results but
> jpeg is so much easier. I think for special photos made and composed
> Raw may be optimal , but its time very consuming.


Agreed. I usually shoot JPEG too. I use RAW only when I know I'm going
to do some extensive work on the picture (difficule shooting conditions,
etc...).

(*) without getting into goory details, JPEG actually encodes luminance
and chrominance separately, and puts less emphasis on chrominance bcause
we are less sensitive to it, so it doesn't really encodes the primmary
colors...

(**) moderns SLRs achieve more than 10 bits most of the time

--
Bertrand
 
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David J Taylor
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Posts: n/a
 
      08-06-2010
"Ofnuts" <(E-Mail Removed)> wrote in message
news:4c5c0239$0$28746$(E-Mail Removed)...
[]
> No... RAW is recommended because JPEG can only code 8 bits per "channel"
> (*). In a camera with significantly more than 8 bits per channel (**)
> going to JPEG requires to discard some information, which cannot be
> recoverdd later. RAW allows these choices to be made later (and pick up
> among them the best choice for a specific photo).

[]
> (*) without getting into goory details, JPEG actually encodes luminance
> and chrominance separately, and puts less emphasis on chrominance bcause
> we are less sensitive to it, so it doesn't really encodes the primmary
> colors...
>
> (**) moderns SLRs achieve more than 10 bits most of the time
>
> --
> Bertrand


Bertrand,

Don't forget that the brightness range coding in RAW is linear, but the
coding in JPEG is "gamma-corrected", meaning that JPEG can actually handle
a /greater/ dynamic range than RAW, but at a lower precision for a given
brightness level.

Where JPEG codes colour differently brightness is in the spatial
resolution. The eye cannot perceive colours as finely (spatially) as it
can greyscale differences, so in JPEG the colour component may only be
encoded at half the resolution (for example, you could look at it as 2 x
2.5MP colour difference images with a 10MP greyscale image). It can
encode primary colours as well as RAW - but at a lower resolution.

Appreciate you are trying to simplify, though.

Cheers,
David

 
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otter
Guest
Posts: n/a
 
      08-06-2010
On Aug 6, 7:27*am, ransley <(E-Mail Removed)> wrote:
> On Aug 6, 7:21*am, Martin Brown <|||(E-Mail Removed)>
> wrote:
>
>
>
>
>
> > On 06/08/2010 13:02, ransley wrote:

>
> > > I use the T1i, dpreview gives a higher rating to Jpeg over Raw. I
> > > believe its because Jpegs settings are optimised by Canon very well.
> > > For my jpegs they come out very good. Is Raw recomended *because jpeg
> > > looses quality every time you open and close it? Is the difference
> > > noticable by opening and closing it say for example 5 times printed at
> > > 5x7 or 8x11? Does the loss on jpeg only occur if you completely close
> > > the photo?

>
> > This is a FAQ and dealt with in the JPEG FAQ. See Q10 of

>
> >http://www.faqs.org/faqs/jpeg-faq/part1/

>
> > Opening and closing a JPEG file doesn't alter it at all unless you Save
> > the file again as a JPEG *and* overwrite the original file. If you treat
> > your original JPEGs are readonly then there is no problem at all.

>
> > The level of degradation with successive saves is not huge provided that
> > you work at a fixed quality level. But it is ever present. This means
> > that in a workflow you want to keep work in progress saved in a lossless
> > format (typically one native to the application you are using that will
> > preserve layers and masks).

>
> > > What are other benefits of Raw to make it worth the extra
> > > hassle of complete editing. I am happy shooting jpeg, I am working
> > > with 5 shot Photomatrix hdr and have done both Raw and jpeg [I think
> > > Photomatrix loaded the jpeg] *I am fully happy with the results but
> > > jpeg is so much easier. I think for special photos made and composed
> > > Raw may be optimal , but its time very consuming.

>
> > Raw gives you more freedom afterwards to rescue dynamic range and adjust
> > colour balance. This can be important if you know that the image will
> > contain black velvet in shadow and a white bridal dress in sunlight. And
> > there is little chance of retaning it if the exposure is even slightly
> > off. It is hard for the in camera auto adjust and save as JPEG to get
> > both exactly right simultaneously and a risk if you let it.

>
> > Most of the time in camera JPEG encoding is fine - ie good enough.
> > (some makers high quality JPEG encoding is better than others)

>
> > Regards,
> > Martin Brown

>
> I use Adobe and just save as it prompts me, is that the proper way? *I
> wonder since Canons jpeg is optimised if I am not going backwards with
> Raw and missing what they have put major effort into perfecting. How
> is dynamic range improved? Color balance controls in editing are the
> same, how is Raw better?- Hide quoted text -
>
> - Show quoted text -


I wouldn't say that the Canon in-camera jpeg routines are better than
what you can achieve in post-processing on a computer. Hasn't been my
experience. The camera/lens correction profiles in ACR 6.1, for
example, alone make it worth switching to shooting RAW, not to mention
the increased ability to make color and exposure corrections without
degrading the image.

I have many jpegs from a few years ago that I was happy with at the
time, but now wish I had shot RAW.

 
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Martin Brown
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Posts: n/a
 
      08-06-2010
On 06/08/2010 13:27, ransley wrote:
> On Aug 6, 7:21 am, Martin Brown<|||(E-Mail Removed)>
> wrote:
>> On 06/08/2010 13:02, ransley wrote:
>>
>>> What are other benefits of Raw to make it worth the extra
>>> hassle of complete editing. I am happy shooting jpeg, I am working
>>> with 5 shot Photomatrix hdr and have done both Raw and jpeg [I think
>>> Photomatrix loaded the jpeg] I am fully happy with the results but
>>> jpeg is so much easier. I think for special photos made and composed
>>> Raw may be optimal , but its time very consuming.

>>
>> Raw gives you more freedom afterwards to rescue dynamic range and adjust
>> colour balance. This can be important if you know that the image will
>> contain black velvet in shadow and a white bridal dress in sunlight. And
>> there is little chance of retaning it if the exposure is even slightly
>> off. It is hard for the in camera auto adjust and save as JPEG to get
>> both exactly right simultaneously and a risk if you let it.
>>
>> Most of the time in camera JPEG encoding is fine - ie good enough.
>> (some makers high quality JPEG encoding is better than others)
>>

> I use Adobe and just save as it prompts me, is that the proper way? I


So long as you don't overwrite original files then yes.

In Photoshop you probably want to use its native format .PSD for
intermediate files or whatever they call it now.

> wonder since Canons jpeg is optimised if I am not going backwards with
> Raw and missing what they have put major effort into perfecting. How


Raw gives you something closer to what the sensor measured which is
between 10 and 12bits of linear intensity data. JPEG gives you 8 bits of
gamma corrected data which depending on the in camera JPEG settings
might result in lost shadow detail or blown highlights. If the shot is
hard to take again then RAW has a major advantage that you can adjust to
get the maximum dynamic range and best colour balance afterwards.

There are a handful of cases where classic JPEG decoder defects mean
that a JPEG is visibly inferior for a few near pathological target
images. Fine black detail on a saturated red flower is one such example.
In this specific case the RAW image is better.

> is dynamic range improved? Color balance controls in editing are the
> same, how is Raw better?


The controls in the programs are identical. You are starting from an
earlier point in the processing chain when you use raw. This can be
useful, but for most casual work it is overkill. You would do better to
concentrate on composition and lighting than worry about RAW vs JPEG.

The generational losses are much less than most people would have you
believe. But they are there. Take an image and using constant quality
settings save a copy image1, close and reload it, then save as image2,
close and reload it then save as image 3. Use the arithemetic functions
to difference them and you will see how much difference there is. Don't
take peoples word for it you can do the experiment yourself.

Regards,
Martin Brown
 
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ray
Guest
Posts: n/a
 
      08-06-2010
On Fri, 06 Aug 2010 05:02:50 -0700, ransley wrote:

> I use the T1i, dpreview gives a higher rating to Jpeg over Raw. I
> believe its because Jpegs settings are optimised by Canon very well. For
> my jpegs they come out very good. Is Raw recomended because jpeg looses
> quality every time you open and close it?


That's not quite true - quality is lost every time it is saved.

> Is the difference noticable by
> opening and closing it say for example 5 times printed at 5x7 or 8x11?


Only if you save it each time - then it will be, eventually.

> Does the loss on jpeg only occur if you completely close the photo? What
> are other benefits of Raw to make it worth the extra hassle of complete
> editing. I am happy shooting jpeg, I am working with 5 shot Photomatrix
> hdr and have done both Raw and jpeg [I think Photomatrix loaded the
> jpeg] I am fully happy with the results but jpeg is so much easier. I
> think for special photos made and composed Raw may be optimal , but its
> time very consuming.


raw gives you greater editing latitude. There is more dynamic range and
every pixel is represented, as opposed to jpeg. With my Kodak P850, I
routinely shoot in raw. In many cases the enclosed jpeg view is adequate
so I don't even process the raw image - simply extract the jpeg. When I
do want to 'tweak' things, it is simple to change, for example, the white
balance - or the exposure setting. If a jpeg is under or overexposed
there is little you can do to correct it - raw has much greater
possibilities.
 
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Barry
Guest
Posts: n/a
 
      08-06-2010
On Fri, 06 Aug 2010 13:21:30 +0100, Martin Brown
<|||newspam|||@nezumi.demon.co.uk> wrote:

>On 06/08/2010 13:02, ransley wrote:
>> I use the T1i, dpreview gives a higher rating to Jpeg over Raw. I
>> believe its because Jpegs settings are optimised by Canon very well.
>> For my jpegs they come out very good. Is Raw recomended because jpeg
>> looses quality every time you open and close it? Is the difference
>> noticable by opening and closing it say for example 5 times printed at
>> 5x7 or 8x11? Does the loss on jpeg only occur if you completely close
>> the photo?

>
>This is a FAQ and dealt with in the JPEG FAQ. See Q10 of
>
>http://www.faqs.org/faqs/jpeg-faq/part1/
>
>Opening and closing a JPEG file doesn't alter it at all unless you Save
>the file again as a JPEG *and* overwrite the original file. If you treat
>your original JPEGs are readonly then there is no problem at all.
>
>The level of degradation with successive saves is not huge provided that
>you work at a fixed quality level. But it is ever present.


Agreed, for the most part, but not always. PhotoLine editor, for example,
does completely lossless JPG editing. The only pixels that change in any
subsequent saves are the ones you specifically change. No other changes are
made to the rest of the image during successive saves. For example you are
working on cloning out a fence-line in a meadow. You do 1/3rd of that
fence, save it as a JPG file, go to lunch. Come back and reopen the image
you previously saved, clone out another 1/3rd of the fence. Get an
important call, so you save your edits to the same JPG file. Come back
later, open it again, finish the project. Save it again. The ONLY pixels
that will have changed during the course of all these editing sessions will
be the fence pixels you changed. Only those pixels that you change are put
through the JPG compression algorithm again during saves. No others
throughout the whole image, nor those in previous edits, will change no
matter how many times you open, edit, save to same file, and open it again.
(See PhotoLine's helpfile on what you can do to override this when needed,
when you intentionally want to lose data with subsequent JPG resaves.)

>This means
>that in a workflow you want to keep work in progress saved in a lossless
>format (typically one native to the application you are using that will
>preserve layers and masks).
>
>> What are other benefits of Raw to make it worth the extra
>> hassle of complete editing. I am happy shooting jpeg, I am working
>> with 5 shot Photomatrix hdr and have done both Raw and jpeg [I think
>> Photomatrix loaded the jpeg] I am fully happy with the results but
>> jpeg is so much easier. I think for special photos made and composed
>> Raw may be optimal , but its time very consuming.

>
>Raw gives you more freedom afterwards to rescue dynamic range and adjust
>colour balance. This can be important if you know that the image will
>contain black velvet in shadow and a white bridal dress in sunlight. And
>there is little chance of retaning it if the exposure is even slightly
>off. It is hard for the in camera auto adjust and save as JPEG to get
>both exactly right simultaneously and a risk if you let it.


It can often get both right, and often does. If you know how to set up your
camera properly to begin with. If you will always be editing your best
shots for prints or before sharing, then shoot with the lowest contrast
setting on your camera that is available. This will ensure retaining the
fullest dynamic range of the RAW sensor data in the resulting JPG file. So
much so that it's difficult to get any extra dynamic range from the RAW
data. Save your more contrasty "impact" edits for later. Unless you never
edit any photos, then let the camera add the "impact" in your images. Then
you're not the kind of photographer that cares all that much about dynamic
range anyway, the content of any images is more important to you than any
fancy editing. Neither way is right or wrong. Good content will always
trump image quality or dynamic range.

Once you've set your JPG to lowest in-camera contrast then get your
exposure right. Those who always work with optical viewfinders are not
aware of how accurately one can predict the final image if they were using
a camera with an EVF (or even LCD). Under/over-exposures are so
20th-century with today's digital cameras that have a decent EVF, if you
know how to use them properly. With an EVF, the exposure and color-balance
that you see in the viewfinder is truly what you get.

One other important tip for those using JPG most of the time. Avoid using
your camera's auto white-balance in most situations. If you know you are
shooting in sunny conditions, use daylight white-balance. If in cloudy
conditions or deep north-light shade, use cloudy white-balance. If under
tungsten lighting, use tungsten white-balance. Etc. Save auto white-balance
for those times when you really don't care how good the image is going to
look and you are willing to put up with odd color-shifts in your images at
times. A good example of this problem was recently posted by a resident
snapshooter. An older fawn in the forest under a deep canopy of green
leaves filtering sunlight. Auto white-balance completely destroyed this
image, turning the fawn into a maroon mess and making all the surrounding
foliage blue and cyan. The camera doesn't know how to properly compensate
for a green light-source such as that coming from all the leaves above and
reflected greens off of the foliage beneath, stripping that color from
everything and throwing them all off. The same would be just as true if you
were shooting a party of people under a bright orange outdoor canopy in
sunlight. Auto white-balance will try to strip out all yellows and reds
(orange) in your image throwing off all skin-tones.

Use the daylight white-balance in these situation because that's your
original light source. Later, in editing, tone down the overall green light
or orange light to something more pleasing, but don't remove it all or
you've destroyed the realism in your image. Whites, blacks, and grays in
the real world are rarely pure white, black, or gray. Snapshooters that
depend on auto-everything, like auto white-balance, don't care if that's
true or not. (Nor do tech-head geeks that live in their basements posting
their "advice" online, never having seen nor experienced the real colors
out in the real world. They insist that whites must be white, grays gray,
and blacks pure black. BTW: This is a good way to spot basement-living
pretend-photographer trolls online.)

A classic example problem for an auto white-balance mistake are those that
shoot spectacular sunsets. The camera's auto white-balance will try to
strip out all the intense golds, reds, and blues of a sunset; muting them
into muddy drab colors; trying to create whites, grays, and blacks amongst
them all. The sun is lighting that sunset so leave your camera on daylight
(sunlight) white-balance and your JPG file will present an image that
looked just like that original rich sunset.

>
>Most of the time in camera JPEG encoding is fine - ie good enough.
>(some makers high quality JPEG encoding is better than others)
>
>Regards,
>Martin Brown

 
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Ofnuts
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Posts: n/a
 
      08-06-2010
On 06/08/2010 14:27, ransley wrote:

> I use Adobe and just save as it prompts me, is that the proper way? I
> wonder since Canons jpeg is optimised if I am not going backwards with
> Raw and missing what they have put major effort into perfecting. How
> is dynamic range improved? Color balance controls in editing are the
> same, how is Raw better?


When you open your original JPEG for editing, do at once a Save As and
pick the Photoshop standard file type (PSD). Thus all mods will apply to
this PSD and will be lossless. Once you are happy with the changes
export to JPEG (under a different name)


--
Bertrand
 
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