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resolution/compression questions from a newbie

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June 11, 2005 9:28:05 AM

Archived from groups: rec.photo.digital (More info?)

Hi,

I have just purchased my first digital camera: a Olympus D-540 Zoom.
Having
read through the (rather louzy) user's manual and a couple of books
from the
local library on digital photography, I am still left with two very
basic
questions:

1) RESOLUTION SELECTION:

My camera offers the following resolutions:

* 640x480 (also identified as SQ2)
* 1600x1200 (also identified as SQ1)
* 2048x1536 (also identified as HQ)
* 2048x1536 (also identified as SHQ)

The camera has 3.2 effective megapixels

I think I understand that the difference between the HQ and SHQ modes
is the
degree of jpeg compression. However, what the manual does not say is
how
important this compression is. My first question is:

Can I use 2048x1536/HQ for 8x10 prints or must I use 2048x1536/SHQ?
What is
*exactly* the difference between the HQ and SHQ modes?

2) JPEG LOSSY COMPRESSION:

I understand that each time a jpeg picture is saved it looses quality
due to the repeated compression. My second question is:

Does this also apply to pictures viewed on the camera's LCD? Does the
camera's
software save the pic each time it is shown on the LCD, or does it
simply
display it on demand and discard the displayed picture each time
without
touching the saved one (which would make more sense to me).

Many thanks in advace for your pointers!
Anonymous
June 11, 2005 4:09:37 PM

Archived from groups: rec.photo.digital (More info?)

"TW" <tuxwins@yahoo.com> wrote in message
news:1118492885.416042.45140@g47g2000cwa.googlegroups.com...
> Hi,
>
> I have just purchased my first digital camera: a Olympus D-540 Zoom.
> Having
> read through the (rather louzy) user's manual and a couple of books
> from the
> local library on digital photography, I am still left with two very
> basic
> questions:
>
> 1) RESOLUTION SELECTION:
>
> My camera offers the following resolutions:
>
> * 640x480 (also identified as SQ2)
> * 1600x1200 (also identified as SQ1)
> * 2048x1536 (also identified as HQ)
> * 2048x1536 (also identified as SHQ)
>
> The camera has 3.2 effective megapixels
>
> I think I understand that the difference between the HQ and SHQ modes
> is the
> degree of jpeg compression. However, what the manual does not say is
> how
> important this compression is. My first question is:
>
> Can I use 2048x1536/HQ for 8x10 prints or must I use 2048x1536/SHQ?
> What is
> *exactly* the difference between the HQ and SHQ modes?

It's a compromise to get more images on a memory card. The less compression
will give you the best image. The question is can you tell the difference.
I suggest you try taking two identical photos using both modes, blow them
both up to 8x10 and see if you can tell the difference.
>
> 2) JPEG LOSSY COMPRESSION:
>
> I understand that each time a jpeg picture is saved it looses quality
> due to the repeated compression. My second question is:
>
> Does this also apply to pictures viewed on the camera's LCD? Does the
> camera's
> software save the pic each time it is shown on the LCD, or does it
> simply
> display it on demand and discard the displayed picture each time
> without
> touching the saved one (which would make more sense to me).
>
> Many thanks in advace for your pointers!

Not sure what you mean here. Are you talking about the image you see before
you take the shot, or the image you see when you review what you've just
taken? The image you see before you take the shot will be the same
regardless of what mode you use, and I don't think you will see much
difference in any mode on that small LCD after the shot is taken. The image
is saved to your memory card. The LCD is just a way to preview and review
the image.
June 11, 2005 4:28:43 PM

Archived from groups: rec.photo.digital (More info?)

Stacey wrote:

> You'll need to go shoot some images at both settings and see for yourself.
> If you're wanting to make 8X10 prints from a 3.2MP camera, I'd be using SHQ
> mode exclusively. I'm sure on some subjects you wouldn't see any difference
> but others it would show up. You won't know until it's too late. CF cards
> are cheap and this camera's files even in SHQ mode aren't that large. If
> you were only making 4X6 prints, HQ would probably be just fine.

The problem is that the file size difference between SHQ and HQ is
really huge. I bought a 128MB card which can hold either about 325 HQs
or 110 SHQs (not exact figures - I have a couple of pictures already on
it). Nor can I afford a bigger card. Do you think 5x7 prints will look
ok with HQ?

> Not at all. What they are talking about is if you open the jpeg in something
> like photo shop, do some deiting and then resave it as a jpeg. Then open
> again, edit some more and resave as a jpeg. That's the sort of thing you
> don't want to do.

That's what I thought but I wanted to check anyway. (although the
program I use - the GIMP 2.0 - allows me to manually set a compression
of my jpegs. I can save without any compression if I want).

Many thanks!

TW
Related resources
June 11, 2005 6:17:34 PM

Archived from groups: rec.photo.digital (More info?)

TW wrote:

> My first question is:
>
> Can I use 2048x1536/HQ for 8x10 prints or must I use 2048x1536/SHQ?
> What is
> *exactly* the difference between the HQ and SHQ modes?

You'll need to go shoot some images at both settings and see for yourself.
If you're wanting to make 8X10 prints from a 3.2MP camera, I'd be using SHQ
mode exclusively. I'm sure on some subjects you wouldn't see any difference
but others it would show up. You won't know until it's too late. CF cards
are cheap and this camera's files even in SHQ mode aren't that large. If
you were only making 4X6 prints, HQ would probably be just fine.


>
> 2) JPEG LOSSY COMPRESSION:
>
> I understand that each time a jpeg picture is saved it looses quality
> due to the repeated compression. My second question is:
>
> Does this also apply to pictures viewed on the camera's LCD?

Not at all. What they are talking about is if you open the jpeg in something
like photo shop, do some deiting and then resave it as a jpeg. Then open
again, edit some more and resave as a jpeg. That's the sort of thing you
don't want to do.
--

Stacey
June 11, 2005 9:30:14 PM

Archived from groups: rec.photo.digital (More info?)

First - thanks to all for your pointers!

Second - I mistakenly identified my memory card as 128MB. It is in
fact 256MB. And yes, Stacy, that us usually plenty enough. But the
problem is that I will be going to a 3 week trip throught the USA and
Canada this summer and I am not at all sure where I will be able to
find a computer with a CD burner and a USB port (software wise I will
take a GNU/Linux live-CD with everything on it which I can use on any
computer, including any Windows machine, without even touching the hard
drives. Just boot-off my live-CD and a complete operating system with
a very good CD-burning application loads itself into memory). I will
try libraries, but many of them do not have computers with USB ports or
CD-burners (and their staff tends to freak out when "strange" software
is run on them).

Of course, I could take a laptop - but that is kind of a pain for a
camping/outdoors -oriented trip.

Anyway - thanks for all the advise and let me know if you have any
ideas where I could transfer my pics from my card to a CD!

Kind regards,

TW
June 11, 2005 11:18:38 PM

Archived from groups: rec.photo.digital (More info?)

TW wrote:

> Stacey wrote:
>
>> You'll need to go shoot some images at both settings and see for
>> yourself. If you're wanting to make 8X10 prints from a 3.2MP camera, I'd
>> be using SHQ mode exclusively. I'm sure on some subjects you wouldn't see
>> any difference but others it would show up. You won't know until it's too
>> late. CF cards are cheap and this camera's files even in SHQ mode aren't
>> that large. If you were only making 4X6 prints, HQ would probably be just
>> fine.
>
> The problem is that the file size difference between SHQ and HQ is
> really huge. I bought a 128MB card which can hold either about 325 HQs
> or 110 SHQs (not exact figures - I have a couple of pictures already on
> it). Nor can I afford a bigger card. Do you think 5x7 prints will look
> ok with HQ?


You have to decide this for yourself. Like I said shoot a scene with some
detail in it at both settings and make a couple of prints. The other
question is how often are you going to need to shoot over 110 images at a
time? That's like 3 rolls of 36 exposures! Also 128MB cards can be had
really cheap these days.. Easily can be had for $20 shipped.

http://tinyurl.com/9vbd4

http://tinyurl.com/8d9br
--

Stacey
Anonymous
June 12, 2005 12:08:44 AM

Archived from groups: rec.photo.digital (More info?)

TW wrote:

<snip>


> The problem is that the file size difference between SHQ and HQ is
> really huge. I bought a 128MB card which can hold either about 325 HQs
> or 110 SHQs (not exact figures - I have a couple of pictures already on
> it). Nor can I afford a bigger card. Do you think 5x7 prints will look
> ok with HQ?

Hi TW...

Just on the off chance that you haven't yet realized it,
you can change qualities mid-stream...

Ken
June 12, 2005 1:59:51 AM

Archived from groups: rec.photo.digital (More info?)

TW wrote:


>
> Anyway - thanks for all the advise and let me know if you have any
> ideas where I could transfer my pics from my card to a CD!
>


Don't most of those kiosk based system offer a CD burning option? Might be a
simple solution if this isn't an often faced problem. You'll be pissed it
you get that "once in a lifetime" shot and it's HQ instead of SHQ. Then
again can't you mix these on the same card? You should be able to see in
the finder if the image looks promising.

--

Stacey
Anonymous
June 12, 2005 5:20:31 AM

Archived from groups: rec.photo.digital (More info?)

On 11 Jun 2005 05:28:05 -0700, "TW" <tuxwins@yahoo.com> wrote:

>My camera offers the following resolutions:
>
>* 640x480 (also identified as SQ2)
>* 1600x1200 (also identified as SQ1)
>* 2048x1536 (also identified as HQ)
>* 2048x1536 (also identified as SHQ)
>
>The camera has 3.2 effective megapixels
>
>I think I understand that the difference between the HQ and SHQ modes
>is the
>degree of jpeg compression. However, what the manual does not say is
>how
>important this compression is.

If you must conserve space, the first you do is to go to a higher
compression level (HQ) - before sacrificing resolution (SQ1).

>Can I use 2048x1536/HQ for 8x10 prints or must I use 2048x1536/SHQ?
>What is *exactly* the difference between the HQ and SHQ modes?

Only the compression level applied for the save JPEGs - a lower
compression level equals higher picture quality. If you can, use
the SHQ always - you will /not/ know beforehand when you need the
better picture quality!

And do backup to other loctions (using cd/dvd) on a regular basis.

>2) JPEG LOSSY COMPRESSION:
>
>I understand that each time a jpeg picture is saved it looses quality
>due to the repeated compression. My second question is:
>
>Does this also apply to pictures viewed on the camera's LCD? Does the
>camera's
>software save the pic each time it is shown on the LCD, or does it
>simply
>display it on demand and discard the displayed picture each time
>without
>touching the saved one (which would make more sense to me).

Displaying the pictures, or even opening them in a picture editing
software and closing it, will do nothing to them.

Just make sure when you edit (correcting redeye, crop, etc) your
pictures that you don't save the edited picture using the same name:

i.e. img0532.jpg should be /saved as/ (something like)

img0532_edited.jpg or img0532_crop.jpg
Anonymous
June 12, 2005 1:56:11 PM

Archived from groups: rec.photo.digital (More info?)

"TW" <tuxwins@yahoo.com> wrote:
>
> Anyway - thanks for all the advise and let me know if you have any
> ideas where I could transfer my pics from my card to a CD!

There are several products about the size of a paperback book that allow you
to download and store images from your cards on an internal hard drive. I
have the Epson P-2000, but it's a tad pricey; I understand there are more
cost-effective products out there. The Epson is nice because the screen is
great, so you can show people images with it.

David J. Littleboy
Tokyo, Japan
Anonymous
June 21, 2005 5:21:12 PM

Archived from groups: rec.photo.digital (More info?)

TW wrote:
> First - thanks to all for your pointers!
>
> Second - I mistakenly identified my memory card as 128MB. It is in
> fact 256MB. And yes, Stacy, that us usually plenty enough. But the
> problem is that I will be going to a 3 week trip throught the USA and
> Canada this summer and I am not at all sure where I will be able to
> find a computer with a CD burner and a USB port (software wise I will
> take a GNU/Linux live-CD with everything on it which I can use on any
> computer, including any Windows machine, without even touching the hard
> drives.

Do yourself a favor: buy a couple of additional CF cards. I personally
prefer 1 Gig cards now, but I shoot sports, and that's usually about
right for one game.

You should be able to find some Gig or half gig cards fairly cheaply.
And in the quiet of the evening it's reasonable to delete the duplicates
and clunkers.

Bon voyage!

--
John McWilliams
!