some newbie questions

Hi,

Some questions about 5M pixels camera (2592 x 1944 )

1. What resolution accept (generally) a professional photo printer (on
plazas, malls)?
People bring 1, 2, 3, 5 M images and print them on the same equipment for
6x4 photos. How the printer "undestand" different resolutions? Does it
"delete" pixels from the high quality photos and "add" them to the pure
ones?

2. Propotions of the photos.
People use the same images for printing 6x4 or 7x5 , etc but at my case 2595
x 1944 is "not good" for any of propotion. Does the printer again "delete"
some portion of photo or I need to prepare my image - create exact 6x4
proportion before printing.

3. I saw the nice examples of photos (good quality in my opinion) on
different sites, but I do not thing that owners upload 5 or 7 M images.
How does it work at such cases? Does they simple convert images to the lower
quality 640k or ever small size?

Thanks

On Tue, 15 Feb 2005 21:54:00 -0500, "Jul"
wrote:

Hi,

Some questions about 5M pixels camera (2592 x 1944 )

1. What resolution accept (generally) a professional photo printer (on
plazas, malls)?
People bring 1, 2, 3, 5 M images and print them on the same equipment for
6x4 photos. How the printer "undestand" different resolutions? Does it
"delete" pixels from the high quality photos and "add" them to the pure
ones?

They accept higher or lower resolution images, and internally adjust
them to the native resolution of the printer. This is typically 300 to
400 ppi. The algorithms involved are more complex than simply dumping
or repeating data.

2. Propotions of the photos.
People use the same images for printing 6x4 or 7x5 , etc but at my case 2595
x 1944 is "not good" for any of propotion. Does the printer again "delete"
some portion of photo or I need to prepare my image - create exact 6x4
proportion before printing.

Usually they crop/zoom so that the smallest dimension fills the
height/width of the printing media. In that sense, the longer
dimension will be cropped equally on both sides, unless you ask it to
do otherwise. Even if you had a perfect match ratio image, to achieve
'full-bleed' all devices will end up cropping a small amount from all
sides.

3. I saw the nice examples of photos (good quality in my opinion) on
different sites, but I do not thing that owners upload 5 or 7 M images.
How does it work at such cases? Does they simple convert images to the lower
quality 640k or ever small size?

Yes, the most common thing would be to resize the image in photo
editing software, making it exactly the right size for the job in
mind. There are other methods. Browsers can resize images based on
HTML supplied dimensions, but this is neither efficient or nice
looking. For good quality, it's important to realize that most images
need to undergo an 'unsharp mask' sharpening filter after being
resized.

Read more on unsharp mask he
http://www.luminous-landscape.com/tu...ding-usm.shtml

--
Owamanga!

In article ,
"Jul" wrote:

Hi,

Some questions about 5M pixels camera (2592 x 1944 )

1. What resolution accept (generally) a professional photo printer (on
plazas, malls)?

Most people agree that a minimum of 200 pixels per inch is necessary,
but if you're used to output from a cheap P&S film camera, then less
than this will be acceptable.

People bring 1, 2, 3, 5 M images and print them on the same equipment for
6x4 photos. How the printer "undestand" different resolutions? Does it
"delete" pixels from the high quality photos and "add" them to the pure
ones?
The printer prints the pixels smaller, I think.

2. Propotions of the photos.
People use the same images for printing 6x4 or 7x5 , etc but at my case 2595
x 1944 is "not good" for any of propotion. Does the printer again "delete"
some portion of photo or I need to prepare my image - create exact 6x4
proportion before printing.

6x4 and 7x5 were designed for the hopelessly long 35mm neg.
A4, B5 and postcard are better for digitals.

3. I saw the nice examples of photos (good quality in my opinion) on
different sites, but I do not thing that owners upload 5 or 7 M images.
How does it work at such cases? Does they simple convert images to the lower
quality 640k or ever small size?

The jpegs are compressed. On websites the screen resolution is a
standard 72 pixels per inch and are usually intended for an 'average'
resolution of around 1000 pixels across the screen. Bigger screens have
higher resolutions but most people don't have them.

Jul wrote:
Hi,

Some questions about 5M pixels camera (2592 x 1944 )

1. What resolution accept (generally) a professional photo printer (on
plazas, malls)?
People bring 1, 2, 3, 5 M images and print them on the same equipment for
6x4 photos. How the printer "undestand" different resolutions? Does it
"delete" pixels from the high quality photos and "add" them to the pure
ones?

The printers would downsample the photos in most cases, which isn't just
deleting pixels.

2. Propotions of the photos.
People use the same images for printing 6x4 or 7x5 , etc but at my case 2595
x 1944 is "not good" for any of propotion. Does the printer again "delete"
some portion of photo or I need to prepare my image - create exact 6x4
proportion before printing.

This is called cropping. Your sensor is a 4:3 sensor. If a photo from your
camera was printed 6 inches wide, it would be 4.5 inches tall. Your camera may
have a 3:2 picture mode so that when you take photos they can be printed out at
6x4 with no cropping.


3. I saw the nice examples of photos (good quality in my opinion) on
different sites, but I do not thing that owners upload 5 or 7 M images.
How does it work at such cases? Does they simple convert images to the lower
quality 640k or ever small size?

You'll probably find that most images on the web are 800 or 1024 pixels wide.
Significantly less than the original, therefore the file sizes are much smaller.
They still look good on the screen, but would not look anywhere near as good as
a similarly sized (physically) print from the original image.

Thanks




--
--
Ben Thomas - Software Engineer - Melbourne, Australia

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