How much information does jpeg lose?

If I shoot RAW and then in Photoshop, export it to a jpeg
with the highest ssetting, how much information is lost?

If I then bring that jpeg into PS and save it as a PSD, how much have
I lost?


--
a d y k e s @ p a n i x . c o m
Don't blame me. I voted for Gore. A Proud signature since 2001

On 15 Apr 2007 11:57:47 -0400, adykes@panix.com (Al Dykes)
wrote:

>
>If I shoot RAW and then in Photoshop, export it to a jpeg
>with the highest ssetting, how much information is lost?

Impossible to quantify. Depends on the contents of the
image.

>If I then bring that jpeg into PS and save it as a PSD, how much have
>I lost?

None.

--
John Bean

2 %

"Al Dykes" <adykes@panix.com> wrote in message
news:evti1r$ci0$1@panix5.panix.com...
>
> If I shoot RAW and then in Photoshop, export it to a jpeg
> with the highest ssetting, how much information is lost?
>
> If I then bring that jpeg into PS and save it as a PSD, how much have
> I lost?
>
>
> --
> a d y k e s @ p a n i x . c o m
> Don't blame me. I voted for Gore. A Proud signature since 2001
>

In article <a7j423lutgag52d016inh7b3pirqb4dcke@4ax.com>,
John Bean <waterfoot@gmail.com> wrote:

> On 15 Apr 2007 11:57:47 -0400, adykes@panix.com (Al Dykes)
> wrote:
>
> >
> >If I shoot RAW and then in Photoshop, export it to a jpeg
> >with the highest ssetting, how much information is lost?
>
> Impossible to quantify. Depends on the contents of the
> image.
>
> >If I then bring that jpeg into PS and save it as a PSD, how much have
> >I lost?
>
> None.

But you do not get back anything you lost with the original JPEG
compression.

--
"When fascism comes to America, it will be wrapped in the flag and
carrying a cross."
Sinclair Lewis

Al Dykes wrote:
> If I shoot RAW and then in Photoshop, export it to a jpeg
> with the highest ssetting, how much information is lost?
>
> If I then bring that jpeg into PS and save it as a PSD, how much have
> I lost?
>

There is no general quantitative answer. It depends on the
amount of detail in the image, including subtle variations
in color.

Ockham's Razor wrote:
> In article <a7j423lutgag52d016inh7b3pirqb4dcke@4ax.com>,
> John Bean <waterfoot@gmail.com> wrote:
>
>> On 15 Apr 2007 11:57:47 -0400, adykes@panix.com (Al Dykes)
>> wrote:
>>
>>> If I shoot RAW and then in Photoshop, export it to a jpeg
>>> with the highest ssetting, how much information is lost?
>> Impossible to quantify. Depends on the contents of the
>> image.
>>
>>> If I then bring that jpeg into PS and save it as a PSD, how much have
>>> I lost?
>> None.
>
> But you do not get back anything you lost with the original JPEG
> compression.

You can do an amazing amount of adjustments to the RAW image itself in
recent versions of ACR and the release version of Lightroom. Using one
of those, you could quickly go back to the source image and start
afresh, or use the full image already adjusted to generate a new TIFF or
PSD.

--
John McWilliams

On Sun, 15 Apr 2007 09:21:23 -0700, Ockham's Razor
<Mencken@pdx.net> wrote:

>In article <a7j423lutgag52d016inh7b3pirqb4dcke@4ax.com>,
> John Bean <waterfoot@gmail.com> wrote:
>
>> On 15 Apr 2007 11:57:47 -0400, adykes@panix.com (Al Dykes)
>> wrote:
>>
>> >
>> >If I shoot RAW and then in Photoshop, export it to a jpeg
>> >with the highest ssetting, how much information is lost?
>>
>> Impossible to quantify. Depends on the contents of the
>> image.
>>
>> >If I then bring that jpeg into PS and save it as a PSD, how much have
>> >I lost?
>>
>> None.
>
>But you do not get back anything you lost with the original JPEG
>compression.

Of course not. But that wasn't the question... or was it?

On reflection perhaps that's what the OP was getting at. In
that case well spotted

--
John Bean

In article <fs2dnezIkr6Qy7_bnZ2dnUVZ_sCinZ2d@comcast.com>,
John McWilliams <jpmcw@comcast.net> wrote:
>Ockham's Razor wrote:
>> In article <a7j423lutgag52d016inh7b3pirqb4dcke@4ax.com>,
>> John Bean <waterfoot@gmail.com> wrote:
>>
>>> On 15 Apr 2007 11:57:47 -0400, adykes@panix.com (Al Dykes)
>>> wrote:
>>>
>>>> If I shoot RAW and then in Photoshop, export it to a jpeg
>>>> with the highest ssetting, how much information is lost?
>>> Impossible to quantify. Depends on the contents of the
>>> image.
>>>
>>>> If I then bring that jpeg into PS and save it as a PSD, how much have
>>>> I lost?
>>> None.
>>
>> But you do not get back anything you lost with the original JPEG
>> compression.
>
>You can do an amazing amount of adjustments to the RAW image itself in
>recent versions of ACR and the release version of Lightroom. Using one
>of those, you could quickly go back to the source image and start
>afresh, or use the full image already adjusted to generate a new TIFF or
>PSD.

What is "ACR". The initials escape me. "A" probably stands for Adobe
but I need to buy another clue.



--
a d y k e s @ p a n i x . c o m
Don't blame me. I voted for Gore. A Proud signature since 2001

In article <14m423pqlqjir8bf8l0hpbmbp22umc1ipq@4ax.com>,
John Bean <waterfoot@gmail.com> wrote:
>On Sun, 15 Apr 2007 09:21:23 -0700, Ockham's Razor
><Mencken@pdx.net> wrote:
>
>>In article <a7j423lutgag52d016inh7b3pirqb4dcke@4ax.com>,
>> John Bean <waterfoot@gmail.com> wrote:
>>
>>> On 15 Apr 2007 11:57:47 -0400, adykes@panix.com (Al Dykes)
>>> wrote:
>>>
>>> >
>>> >If I shoot RAW and then in Photoshop, export it to a jpeg
>>> >with the highest ssetting, how much information is lost?
>>>
>>> Impossible to quantify. Depends on the contents of the
>>> image.
>>>
>>> >If I then bring that jpeg into PS and save it as a PSD, how much have
>>> >I lost?
>>>
>>> None.
>>
>>But you do not get back anything you lost with the original JPEG
>>compression.
>
>Of course not. But that wasn't the question... or was it?
>
>On reflection perhaps that's what the OP was getting at. In
>that case well spotted
>


I know that you can't replace lost info and that saving a jpeg on
itself is a Bad Idea.

Thanks



--
a d y k e s @ p a n i x . c o m
Don't blame me. I voted for Gore. A Proud signature since 2001

On 15 Apr 2007 12:57:08 -0400, in rec.photo.digital adykes@panix.com (Al
Dykes) wrote:


>What is "ACR". The initials escape me. "A" probably stands for Adobe
>but I need to buy another clue.

Adobe Camera Raw. The raw converter in PS. PSE and other Adobe products.
--
Ed Ruf (Usenet2@EdwardGRuf.com)
http://edwardgruf.com/Digital_Photog...ral/index.html