RetouchPRO

Go Back   RetouchPRO > Technique > Image Help
Register Blogs FAQ Site Nav Search Today's Posts Mark Forums Read


Image Help Got a problem image? Don't know where to begin? Upload images and ask our users what they think or if they can help

enquiry about resolution

Reply
 
Thread Tools
  #1  
Old 05-24-2005, 06:57 AM
cjparra cjparra is offline
Junior Member
 
Join Date: May 2005
Posts: 4
enquiry about resolution

Hi, we have a different opinion between my brother and me about a so basic and at once vital conception like resolution. I hope a enquiry about it be appropriate in this forum. I put below the two versions and I would be grateful for any help in order to determine which is the right one. Thank you very much indeed in advance.

Version 1:

1.a. The image size professionally is, in both analog and digital, measured in metric units (centimeters and its multiples or inches). And the resolution is always measured in pixels/metric unit. The result of this two variables (which is a specific amount of pixels) is, in general conceps in digital photography, only the resulting amount of pixels, only that. Finding a reason for what in some digital cameras is erroneously spoken about «image size» in pixels without that image being for the web, I find that really there is a fixed relation between size and pixels, independently of resolution, but it refers to the image file’s size, measured in MB, which certainly is always directly proportional to the amount of pixels.

1.b. When we do a photo with a digital camera, the size is always the same, those that lens is able to catch. And resolution is the amount of pixels in which that photo is going to turn into, in other words, the density of pixels that a size of photo is going to be: those that lens is able to catch and give to the «scanner» of the camera in order to transform it by the scanner in a whole spectrum of pixels, and which is going to determine the accuracy of the photo’s details, that is: its resolution.

Version 2:

2.a. In photography with digital camera, resolution (px/cm, px/inch) doesn’t exist, photography with digital camera exclusively works with image size in pixels, which is named resolution. The same occurs in digital image in screen (for example web, also screen proyection): photography with digital camera exclusively works with image size in pixels, which is named resolution.

2.b. In photography with digital camera, the size of the caught photo isn’t always the same: generally, the photosensor is a Area Array CCD, that consists in a reticulated matrix of hundred of thousands of microscopic photosensitive cells (photodiodes). Each photodiode matchs with one pixel, so the more photosensor the CCD have, the better the quality obtained with the camera will be. Those number of photosensors can be associated to a physical size (that which they themselves take up inside the camera, that isn’t the one of the image because it doesn’t exist as we physically know it), this physical size in any case would be variable by changing the resolution with which we take the photo (size in pixels x pixels).
Reply With Quote top
  #2  
Old 05-24-2005, 04:24 PM
byRo's Avatar
byRo byRo is offline
Senior Member
 
Join Date: May 2004
Location: Goianésia, Brazil
Posts: 1,609
Hi there, cjparra, welcome to RP

Not very easy reading there, though 2) seems a little closer.
Try thinking another way....

When something is purely digital the only thing that makes any sense is total pixel dimensions.

However this purely digital image has to have some interfaceswith the real world and this is where the pixels/inch stuff comes in. The interfaces are at the entry point (scanner / camara), the manipulation (monitor) and the final product (printing).

In short there is no such thing a resolution for the digital image file, only pixel dimensions.
Resolution at the interfaces is just a measurement of the quality (or the settings) of the equipment being used to translate between the digital and analogue worlds.

Hope this helps a bit, if not just ask more.

Reply With Quote top
  #3  
Old 05-24-2005, 04:42 PM
cjparra cjparra is offline
Junior Member
 
Join Date: May 2005
Posts: 4
Thanks

Of course your reply definitely helps. Only a doubth: in a digital camera (even though I know this forum isn't about digital photograph), can you set the resolution (px/inch or px/cm) of the image or you only can set its size (px)¿¿?? And, could you say anything about the second question: with digital camera is possible to talk about the physical size of the caught photo or the physical size doesn't exist because in the camera we only have pixels¿?
Reply With Quote top
  #4  
Old 05-24-2005, 05:08 PM
byRo's Avatar
byRo byRo is offline
Senior Member
 
Join Date: May 2004
Location: Goianésia, Brazil
Posts: 1,609
Inside the camara there is a little array of CCD's (or something similar). This array has a pre-defined quantity of elements which correspond to the pixel capacity of the camara.
The lens adapts any analogue image (from a postage stamp to the moon) entering the camara to fall on the array. All of this optical stuff is completely variable, but the end result will always be fixed number of pixels.

Resuming: Digital Camara = Light in - pixels out.

There is no place where you can meaningfully talk about px/inch, except at the CCD sensor - and that measurement only interests camara makers and not camara users.

Reply With Quote top
  #5  
Old 05-24-2005, 05:35 PM
cjparra cjparra is offline
Junior Member
 
Join Date: May 2005
Posts: 4
Quite clear. Thanks for all Rô
Reply With Quote top
  #6  
Old 05-25-2005, 01:39 AM
Gary Richardson's Avatar
Gary Richardson Gary Richardson is offline
Senior Member
 
Join Date: Mar 2004
Location: Yorkshire, England
Posts: 2,717
Just one thing to add here.

On some cameras there are settings that will allow different portions of the CCD to be used, thus the total number of pixels in the image can be varied.

This is done to enable more images of less quality, or fewer of greater quality, to be stored on a memory stick.
Reply With Quote top
  #7  
Old 05-25-2005, 06:25 AM
cjparra cjparra is offline
Junior Member
 
Join Date: May 2005
Posts: 4
Yes, in fact the size of the image in pixels, I think. Thanks for reply
Reply With Quote top
Reply

  RetouchPRO > Technique > Image Help


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Is resolution Stricly confined to a Screen? Donamai Image Help 9 07-01-2007 03:35 PM
48bit Scanner Resolution and PS Questions Lucile Davis Hardware 13 08-20-2006 09:51 PM
Resolution Old Phogey Hidden Power Support 8 11-05-2003 02:28 PM
5 questions concerning resolution Ed_L Input/Output/Workflow 2 12-19-2001 11:13 PM
Newbie printing question Doug Nelson Input/Output/Workflow 0 08-08-2001 12:30 PM


All times are GMT -6. The time now is 12:14 PM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
SEO by vBSEO ©2011, Crawlability, Inc.
Copyright © 2016 Doug Nelson. All Rights Reserved