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Old May 28, 2003, 5:36 PM   #21
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I would agree with billdrew when saying cropping a 2272x1704 photo down to 1280x960 is not the same as a 3x zoom. when u crop an image you are not zooming at all you are just changing its dimensions
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Old May 28, 2003, 8:13 PM   #22
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Quote:
Originally Posted by Colt-45
You said you don't have a printer, do you have any of your images printed? or do you just have them on your comp?
Personally I don't feel the need to print any photos out. It's so convenient just to store them all on my computer so I can look at them whenever I like. I also don't like acquiring physical posessions and making prints of all my photos would just mean having to make cupboards to store them all on. It would be a waste of space.

My screen is much bigger than any photo I would print out, and I like seeing my photos big and presented the way they were meant to be (illuminated, with primary colours). Yeah, I realise, screens aren't really as good a quality as prints, but I'm not too bothered right now cos in the future screens will be bigger and much higher resolution. And as you know, photos look good on screen.

I do make prints from time to time though. Just for other people. I do theatre so I like to take a load of photos of everyone and make prints for anyone that wants them. The professionals charge ridiculous amounts!

I always get my prints done with Jessops, a camera company here in the UK.
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Old May 28, 2003, 8:16 PM   #23
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Can anyone please explain to me how cropping an image is not the same as zooming. I realise the resolution will be lower (duh!) but surely it will be exactly the same photo as if you had zoomed in.

I can't quite understand how it could possibly be any different.

This has stumped me! (My turn to be the newbie.)

And why can't I consider my camera to have 9.5x zoom capability at 1280x960? Surely the objects in the photo appear 9.5 times bigger than they would appear had I not zoomed in 3x and cropped the image to just under a third its original size.

I'm certian of this. Do I have to experiment to prove it? Or are you guys just winding me up?
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Old May 28, 2003, 10:25 PM   #24
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Quote:
Originally Posted by Grand Dizzy
Can anyone please explain to me how cropping an image is not the same as zooming. I realise the resolution will be lower (duh!) but surely it will be exactly the same photo as if you had zoomed in.

I can't quite understand how it could possibly be any different.
The average human eye has a focal length ~50mm (35mm equivalent). Concentrate on a particular object.

Now take a piece of paper and cut a small square hole in it large enough to see the object, and hold up the paper so you can see the object through the hole.

Have you zoomed in on the object (does the object look closer to you, or look larger)?

All you did was get rid of some extra information. The focal length is still ~50mm.


Anyway, you got it *half* right, but you're missing the other half of the equation. The missing step would be after cropping that picture down to 1280x960 you'd then enlarge it back to 2272x1704...that would be what a digital zoom does.
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Old May 29, 2003, 2:44 AM   #25
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I'm certian [sic] of this. Do I have to experiment to prove it? Or are you guys just winding me up?[/quote]

Nobody is winding you up. If your cropped picture, immediately after cropping, has more pixels than your computer screen has, you will see no difference on screen. But do as you suggest and make an A4 print from each and look at the sharpness. I think then you will understand. The cropped picture will be less sharp than the zoomed picture.
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Old May 29, 2003, 6:14 PM   #26
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I'll take your word for it (I dont' wanna waste money printing out test photos!)

What you seem to be saying is this...

If you take a 1 megapixel photo on a 1 megapixel camera, will get a photo that is a certain "sharpness". But if you take a 4 megapixel photo on a 4 megapixel camera, the resulting photo will have exactly the same level of "sharpness".

In other words, the higher the resolution of your camera, the lower the sharpness gets of the pixels.

So in theory, if you had a very high resolution camera (a million quillion megapixels) then a 1 megapixel area of it would just look blurry and you wouldn't be able to make out any detail at all. In other words, each pixel of the sensor would not be resolving properly. They'd all just be blurring together.

In other words, the more megapixels a camera has, the more useless the pixels are because they lose their definition.

So more megapixels doesn't mean more detail at all. It just means more pixels are give to the same image, and a higher resolution camera doesn't capture any more detail than a 1 megapixel camera. It actually has less detail, in terms of sharpness.

That can't be right... surely?

If each individual pixel of the sensor is not resolving an independent colour - then what is it there for? What is the point in buying a higher resolution camera? And what specification must be high in order for the sharpness of the image to be higher?

I bought a 4 megapixel camera because I wanted photos that were made up of 3871488 individually coloured pixels taken by 3871488 independent light sensors.

If I took a photo of a page of a book with a 1 megapixel camera, I wouldn't expect to be able to read the text as clearly as with a 4 megapixel camera.

Are you saying that it's exactly the same level of clarity no matter how many megapixels are used?

If the resolution of the camera makes no difference to the image sharpness then why doesn't everyone just but 1 megapixel cameras?
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Old May 29, 2003, 7:43 PM   #27
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Quote:
Originally Posted by Grand Dizzy
If the resolution of the camera makes no difference to the image sharpness then why doesn't everyone just but 1 megapixel cameras?
The amount of information that is needed to make prints is more. The *minimum* you need for 8"x10" for instance is 2mp...if you blow up a 1mp picture to 8x10 it will look like garbage!
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Old May 29, 2003, 8:52 PM   #28
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Quote:
If you take a 1 megapixel photo on a 1 megapixel camera, will get a photo that is a certain "sharpness". But if you take a 4 megapixel photo on a 4 megapixel camera, the resulting photo will have exactly the same level of "sharpness".
What is your definition of "sharpness"? My definition of sharpness is that the picture can represent detail to a level that fits my memory of the scene. That the detail that I saw is represented in the picture. This is effected by the medium used to display the picture, of course. But assuming I have more resolution in my output device than I have data in the picture, the 4MP picture of exactly the same scene will be sharper, it will not have the same level of sharpess.

I don’t see how this definition works with the above quote from your argument. So I can only conclude that you are using a different definition.

A very high resolution camera (a million quillion megapixels) used to take exactly the same picture will exceed the maximum “sharpness” for my output device (assuming the photosites on the sensor aren’t smaller than a wavelength of visible light… then the photosites are really wasted!) The advantage would be that I could crop and enlarge a reasonable section of the image and it would still be greater than the maximum “sharpness” for my output device (for the same size print.) So the “sharpness” would be the same in the crop or the original. But that is a limitation of my output device, not the camera. With a million quillion DPI output device, viewed at a reasonable distance, the cropped picture enlarged to the same size would look different. It would be less sharp.

I would reword this quote of yours:
Quote:
In other words, the more megapixels a camera has, the more useless the pixels are because they lose their definition.
As “In other words, the more megapixels a camera has, the more details the picture can capture.” You might not be able to output that amazingly fine detail, but that is not the camera’s fault.

Here is my simple example. If you have a 1 pixel camera, it clearly won’t represent the scene very well. As you add more pixels represent the scene, more detail will be shown. The picture will be sharper. As seen above, there is a point where you become output limited. But more data doesn’t make each pixel less sharp.

I could go on, but since I think we are talking from different points of view, it doesn’t seem… well, worth it. There is a fundamental misunderstanding/different between our positions that needs to be addressed first.
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Old May 30, 2003, 3:12 AM   #29
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If you take a 1 megapixel photo on a 1 megapixel camera, will get a photo that is a certain "sharpness". But if you take a 4 megapixel photo on a 4 megapixel camera, the resulting photo will have exactly the same level of "sharpness".

Lets get back to basics. If your monitor screen runs at 1024x768, then it has 1024x768=786483 pixels. Whatever number of pixels your picture has, if it is more than this number there will be no improvement seen on the monitor. If the picture has less pictures than this, you will see blocks of pixels rather than individual pixels and the picture will look less sharp. [For the pedantic reader, I am ignoring improvement seen in the reduced compression effects of a large image on a smaller screen].

In other words, the higher the resolution of your camera, the lower the sharpness gets of the pixels.
So in theory, if you had a very high resolution camera (a million quillion megapixels) then a 1 megapixel area of it would just look blurry and you wouldn't be able to make out any detail at all. In other words, each pixel of the sensor would not be resolving properly. They'd all just be blurring together.
In other words, the more megapixels a camera has, the more useless the pixels are because they lose their definition.
So more megapixels doesn't mean more detail at all. It just means more pixels are give to the same image, and a higher resolution camera doesn't capture any more detail than a 1 megapixel camera. It actually has less detail, in terms of sharpness.


How on earth do you come to this conclusion? If as you do, you only look at your digital pictures on the monitor, it really does not matter a toss what your camera is, unless you want all the bells and whisles and a piece of flash male jewelery. A cheapo 1 megpixel 3x zoom would be good enough. But many people want to print their pictures. Let me try to explain. My 5 mpixel camera produces a picture 2560x1920 pixels [about 5 mpixels]. If I print this at say 12"x9", there will be 213 pixels per inch. In other words I will have 213 dots per inch of information on the print. If I have a camera that produces a picture say 1280x960 [1.3 mpixels] and I print it at 12"x9", then there will be only 107 dots per inch of the print. Surely you can realise that a print at 213 dots per inch of information will produce a sharper print than 107 dots of information per inch.


And what specification must be high in order for the sharpness of the image to be higher?

That should now be clear.

I bought a 4 megapixel camera because I wanted photos that were made up of 3871488 individually coloured pixels taken by 3871488 independent light sensors.

And within the capability of your understanding [because it is not actually like that] that is what you get. But you computer monitor does not have 3,871,488 independant dots of light, it has less than 1,000,000 as previously described. So you cannot see 3,871,488 dots on your screen, can you?

If I took a photo of a page of a book with a 1 megapixel camera, I wouldn't expect to be able to read the text as clearly as with a 4 megapixel camera.

And that is correct, unless you are looking at the picture on your monitor, with the picture filling the monitor, then there would be no difference. But if you zoomed-in on your monitor, you would be able to read smaller print more easily from the 4 mpixel image than from the 1 mpixel image. Because each letter you were trying to read would have 4x the number of dots of information [pixels] and that would make it "sharper".

Are you saying that it's exactly the same level of clarity no matter how many megapixels are used?

A pixel is a pixel. There are no sharp or fuzzy pixels. A pixel is a pixel. More pixels= bigger prints for anY fixed level of " sharpness".

If the resolution of the camera makes no difference to the image sharpness then why doesn't everyone just but 1 megapixel cameras?

THE NUMBER OF PIXELS MAKES NO DIFFERENCE ON THE SCREEN, BUT WE BUY MORE PIXELS BECAUSE WE PRINT OUR PICTURES
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Old May 30, 2003, 8:15 AM   #30
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This is totally confusing me! Let's start at the beginning again.

Here is the original statement that stumped me (and still does):

Quote:
Originally Posted by BillDrew
Quote:
Originally Posted by Grand Dizzy
My camera is 3x zoom, but I consider it to be 9.5x zoom if I crop the photo down to 1280x960.
You might consider it to be a 9.5x zoom, but no one else would.
This was backed up by Kschewe:

Quote:
Originally Posted by kschewe
I would agree with billdrew when saying cropping a 2272x1704 photo down to 1280x960 is not the same as a 3x zoom. when u crop an image you are not zooming at all you are just changing its dimensions
Everyone seems to be in agreement that cropping an image down is not the same thing as zooming.

In other words, a 2 megapixel photo taken at 2x zoom will result in a different photo to a 4 megapixels photo that has been cropped down to 2 megapixels.

In other words, 3x is the the most I can zoom with my 3x zoom camera. Because cropping isn't zooming.

For this to be true; for these to produce two different photos, then cameras must give less detail at higher resolutions.

I have always assumed that if I use twice the number of pixels to take a photo, then I should have twice as much detail. So I should be able to zoom out and get twice as much in the photo, and still make out exactly the same details as I could see with half the number of pixels. Because the original area of the photo is still covered by as many pixels as it used to be.

If I can't see that detail any more, then the camera must be giving me less detail at higher resolutions. And therefore having more pixels is pointless.

If 4 megapixel cameras take exactly the same photo as 1 megapixel cameras (only with 4 times the number of pixels) then you may as well just take the photos at 1 megapixel setting and scale them up to 4 megapixels on the computer. That way you can store 4 times as many photos on the camera's memory.

If that isn't the case, then 4 megapixel photos do give 4 times more detail. And therefore you should be able to crop them down to a fourth of their size and still get the same level of detail as a 1 megapixel photo.

And therefore zooming by cropping is perfectly acceptible.
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