Zooming and Cropping

geezer

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I have a Toshiba 3.2 PDR 3300 camera.

I took a group shot of 6 people.
I uploaded the pic to PC via Picasa.
I input it to Photoshop - Its resolution was 72.
I changed its size to 8"W X 10"H.
I printed it and the result was just dandy.
I cropped out each of the people, resized each to 8"W X 10"H.
I printed them and all 6 were grainy.

What did I do wrong?

Thanks
 
G

Guest

Guest
Archived from groups: alt.comp.periphs.dcameras (More info?)

You didn't do anything wrong. There are a finite number of pixles in your
original image. When you take a small area of the original image and blow
it up, you have only a small number of pixles to cover a large (8x10) area.
For example, your original image may have 2048 x 1536 pixels. That's enough
to cover a print at 8"x10" at 300dpi (average inkjet resolution). When you
crop a small area, you might cut the image down to, say, 250x250 pixels.
Now you are asking those 250 pixels to cover a much bigger area when you
blow it up. When you use your software to increase the size, the software
will "guess" or interpolate the additional pixels needed to make the image
bigger. This is an imperfect process because the software doesn't have
enough pixel information to produce a smooth high resolution image.

Some possible solutions:

- Take pictures of each face individually and have the portrait cover the
entire original image.
- Get a camera with more megapixels. The more pixels you have, the more you
can blow it up - so you might get away with blowing up small areas of the
image. (not the best solution, obviously)

- If you need to get a better image from your existing image - because you
can't reshoot it - you *could* try to use your image software to process the
image more. In Photoshop, I might use 'gaussian blur' and then maybe
'sharpen' tools to *try* to squeeze a better image from a few pixels. But
it will never be perfect.

Think of it this way. If you have 1000 bricks, you might be able to build a
very small house. If you try to build a large house with 1000 bricks, there
will be huge gaps between the bricks. You could trowl a bunch or mortar in
between the bricks to spread them out, but the walls would look lumpy and
irregular. Your image processing software is trying to take a small house
(image) and stretch it into a big house. But there are not enough bricks
there to make a bigger house, so the software makes up for it by using
mortar to fill the gaps. These mortar-filled gaps will never look as smooth
as if you used enough bricks.

Did that make any sense?

Here's some more info...
http://www.vividlight.com/articles/3116.htm

best regards,
Jack




"geezer" <wee@willy.com> wrote in message
news:ebeh21d6be9hmd6erithsi56klk5u72c7e@4ax.com...
> I have a Toshiba 3.2 PDR 3300 camera.
>
> I took a group shot of 6 people.
> I uploaded the pic to PC via Picasa.
> I input it to Photoshop - Its resolution was 72.
> I changed its size to 8"W X 10"H.
> I printed it and the result was just dandy.
> I cropped out each of the people, resized each to 8"W X 10"H.
> I printed them and all 6 were grainy.
>
> What did I do wrong?
>
> Thanks
 

geezer

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Feb 18, 2002
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Archived from groups: alt.comp.periphs.dcameras (More info?)

On Fri, 04 Mar 2005 21:12:24 GMT, "MostlyH2O" <jmc@takeitouthrmp.net>
wrote:

>You didn't do anything wrong. There are a finite number of pixles in your
>original image. When you take a small area of the original image and blow
>it up, you have only a small number of pixles to cover a large (8x10) area.
>For example, your original image may have 2048 x 1536 pixels. That's enough
>to cover a print at 8"x10" at 300dpi (average inkjet resolution). When you
>crop a small area, you might cut the image down to, say, 250x250 pixels.
>Now you are asking those 250 pixels to cover a much bigger area when you
>blow it up. When you use your software to increase the size, the software
>will "guess" or interpolate the additional pixels needed to make the image
>bigger. This is an imperfect process because the software doesn't have
>enough pixel information to produce a smooth high resolution image.
>
>Some possible solutions:
>
>- Take pictures of each face individually and have the portrait cover the
>entire original image.
>- Get a camera with more megapixels. The more pixels you have, the more you
>can blow it up - so you might get away with blowing up small areas of the
>image. (not the best solution, obviously)
>
>- If you need to get a better image from your existing image - because you
>can't reshoot it - you *could* try to use your image software to process the
>image more. In Photoshop, I might use 'gaussian blur' and then maybe
>'sharpen' tools to *try* to squeeze a better image from a few pixels. But
>it will never be perfect.
>
>Think of it this way. If you have 1000 bricks, you might be able to build a
>very small house. If you try to build a large house with 1000 bricks, there
>will be huge gaps between the bricks. You could trowl a bunch or mortar in
>between the bricks to spread them out, but the walls would look lumpy and
>irregular. Your image processing software is trying to take a small house
>(image) and stretch it into a big house. But there are not enough bricks
>there to make a bigger house, so the software makes up for it by using
>mortar to fill the gaps. These mortar-filled gaps will never look as smooth
>as if you used enough bricks.
>
>Did that make any sense?
>
>Here's some more info...
>http://www.vividlight.com/articles/3116.htm
>
>best regards,
>Jack
>

Thanks Jack

Let me throw this at you.

This camera has 3 'size' settings and 3 'quality' settings.
I tried all 9 combos.
When I uploaded all 9, Photoshop insisted that all of them were
resolution of 72. Is that proper?
Also, I did not see any difference in the image qualities in the 9.
However, camera memory and PC file sizes were greatly affected.

Thanks
 
G

Guest

Guest
Archived from groups: alt.comp.periphs.dcameras (More info?)

On Fri, 04 Mar 2005 21:21:50 GMT, geezer <wee@willy.com> found these unused
words floating about:

>On Fri, 04 Mar 2005 21:12:24 GMT, "MostlyH2O" <jmc@takeitouthrmp.net>
>wrote:
>
>>You didn't do anything wrong. There are a finite number of pixles in your
>>original image. When you take a small area of the original image and blow
>>it up, you have only a small number of pixles to cover a large (8x10) area.
>>For example, your original image may have 2048 x 1536 pixels. That's enough
>>to cover a print at 8"x10" at 300dpi (average inkjet resolution). When you
>>crop a small area, you might cut the image down to, say, 250x250 pixels.
>>Now you are asking those 250 pixels to cover a much bigger area when you
>>blow it up. When you use your software to increase the size, the software
>>will "guess" or interpolate the additional pixels needed to make the image
>>bigger. This is an imperfect process because the software doesn't have
>>enough pixel information to produce a smooth high resolution image.
>>
>>Some possible solutions:
>>
>>- Take pictures of each face individually and have the portrait cover the
>>entire original image.
>>- Get a camera with more megapixels. The more pixels you have, the more you
>>can blow it up - so you might get away with blowing up small areas of the
>>image. (not the best solution, obviously)
>>
>>- If you need to get a better image from your existing image - because you
>>can't reshoot it - you *could* try to use your image software to process the
>>image more. In Photoshop, I might use 'gaussian blur' and then maybe
>>'sharpen' tools to *try* to squeeze a better image from a few pixels. But
>>it will never be perfect.
>>
>>Think of it this way. If you have 1000 bricks, you might be able to build a
>>very small house. If you try to build a large house with 1000 bricks, there
>>will be huge gaps between the bricks. You could trowl a bunch or mortar in
>>between the bricks to spread them out, but the walls would look lumpy and
>>irregular. Your image processing software is trying to take a small house
>>(image) and stretch it into a big house. But there are not enough bricks
>>there to make a bigger house, so the software makes up for it by using
>>mortar to fill the gaps. These mortar-filled gaps will never look as smooth
>>as if you used enough bricks.
>>
>>Did that make any sense?
>>
>>Here's some more info...
>>http://www.vividlight.com/articles/3116.htm
>>
>>best regards,
>>Jack
>>
>
>Thanks Jack
>
>Let me throw this at you.
>
>This camera has 3 'size' settings and 3 'quality' settings.
>I tried all 9 combos.
>When I uploaded all 9, Photoshop insisted that all of them were
>resolution of 72. Is that proper?
>Also, I did not see any difference in the image qualities in the 9.
>However, camera memory and PC file sizes were greatly affected.
>
>Thanks
>
Photoshop resizes the image to 'fit' the working window for display only. It
does NOT alter the actual image.

Take and use the 'zoom' controls to set the images to 100% each and you'll
see the difference!

The CAMERA is insisting they are all 'sized' for 72dpi, not photoshop! Bad
Camera !!!
 

geezer

Distinguished
Feb 18, 2002
114
0
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Archived from groups: alt.comp.periphs.dcameras (More info?)

On Fri, 04 Mar 2005 15:39:58 -0800, J. A. Mc. <jaSPAMc@gbr.online.com>
wrote:


>Photoshop resizes the image to 'fit' the working window for display only. It
>does NOT alter the actual image.
>
>Take and use the 'zoom' controls to set the images to 100% each and you'll
>see the difference!
>
>The CAMERA is insisting they are all 'sized' for 72dpi, not photoshop! Bad
>Camera !!!


Whose 'Zoom' controls? Photoshop's?

Thanks for response.
 
G

Guest

Guest
Archived from groups: alt.comp.periphs.dcameras (More info?)

> This camera has 3 'size' settings and 3 'quality' settings.
> I tried all 9 combos.
> When I uploaded all 9, Photoshop insisted that all of them were
> resolution of 72. Is that proper?

Yea - mine does that too. 72 dpi is only relevant if you also look at the
image size. If you look at the sizes of your 9 images, the higher 'quality'
ones should be bigger (have more pixels - or inches - whatever incriment you
are using). The "dpi" really refers to the method of output/viewing of your
image - not the resolution.

-- 72dpi (dots per inch) is the resolution of your computer monitor. So for
every square inch that you see on your computer monitor, you are seeing
72x72 pixels. This will never change....

-- Imagine that you have a single image that is 72x72 pixels. Since your
computer monitor can only display 72dpi, your image will be 1" x 1"...

-- Your inkjet printer can print at a much higher resolution than your
monitor displays - 300dpi. So for every square inch you see on a printed
page, there can fit 300x300 pixels. That's about 4 times as many pixels in
an inch compared to the monitor. Now, if you take the above 72x72 pixel
image and print it on your 300dpi inkjet printer, your image will only be
about 0.25"x0.25" (one quarter the size displayed on your monitor)- because
you need 300x300 pixels to fill an inch - but you only have 72x72.

-- So the "DPI" refers to your output. What maters is the actual "X" and
"Y" size of the image. Your 3 megapixel camera can make an image of up to
2048x1536 pixels (approximately). Your inkjet printer prints 300x300 pixels
in a square inch, so your printed picture will be 6.82 inches by 5.12
inches. You see? - you have to print 2048 pixels accross the page - and can
fit 300 pixels in an inch - so 300 pixels times 6.82 inches = 2048.

- But your computer monitor displays only 72 pixels in an inch - so to
display all 2048 pixels (at 1:1 zoom - or 100%), you would need a monitor
that was 28.4 inches wide! That's why digital camera images always look
HUGE on your monitor - unless you are zoomed out. Photoshop will "Zoom to
fit" the image when you first open it. If you are looking at your entire
image in photoshop, (double click the magnifying glass to see the image at
it's true 100% or 1:1 size. Of course, zooming in our out of the image in
photoshop does not affect the actual resolution of the image - just the way
you see it.

> Also, I did not see any difference in the image qualities in the 9.

That's probably because you are looking at them all way zoomed out - so you
can't see the detail. Notice the status bar just above your image - it
probably says something like "1:3" or "1:4". When you double click the
magnifying glass tool, you will be looking at it 1:1 - or 100% size. If you
do this, you will see that some images are bigger (have more pixels) than
others. The more pixels you have, the larger an image you can print or view
at 100% or 1:1. Now you can always take an image with fewer pixels and
artificially blow up the size with your software or print settings, but then
you run into the problem we discussed at the begining of this thread.

> However, camera memory and PC file sizes were greatly affected.

Right. more pixels takes more memory. Let's imagine that your camera does
the following:

Low Quality Image = 640x480 pixels
Medium Quality = 600x800 pixels
High Quality = 2048x1536 pixels

If you compare the high quality and the low quality images (both at 100% or
1:1 - this is important) - you should see a considerable difference in the
detail. If you are zoomed out on the images, you won't notice the
difference as much. If you print both images on your inkjet (again, each at
100%) high quality will be bigger than the low quality. If you take the low
quality image and artificially blow it up, the quality of the image will
not be as good as if you used high quality image - because there's not as
much pixel information for a good image.

OK - going to cook dinner now ;-)
 
G

Guest

Guest
Archived from groups: alt.comp.periphs.dcameras (More info?)

On Sat, 05 Mar 2005 00:00:26 GMT, geezer <wee@willy.com> found these unused
words floating about:

>On Fri, 04 Mar 2005 15:39:58 -0800, J. A. Mc. <jaSPAMc@gbr.online.com>
>wrote:
>
>
>>Photoshop resizes the image to 'fit' the working window for display only. It
>>does NOT alter the actual image.
>>
>>Take and use the 'zoom' controls to set the images to 100% each and you'll
>>see the difference!
>>
>>The CAMERA is insisting they are all 'sized' for 72dpi, not photoshop! Bad
>>Camera !!!
>
>
>Whose 'Zoom' controls? Photoshop's?
>
>Thanks for response.
>
CTRL+ALT+(+/-)

You might find pressing F1 a great help.
 
G

Guest

Guest
Archived from groups: alt.comp.periphs.dcameras (More info?)

Sounds like a visit to www.scantips.com might be in order to get a good
grasp on resolution..