What may cause the image unclear?

[coody]

I got some pictures by email. The size are from 1335 to 1778 bytes. The Dimensions are 67X90 pixels. The size is small. By zooming in, the pictures become unclear. Is it because the sender’s digital camera's MP is not high enough or the picture has been reduced the size before emailing? I also noticed some pictures (by uploading) on some website are clear while some are not after zooming in.

[filmboss80]

Coody, are you kidding us with these kinds of questions? Does it not occur to you that more pixels equals more detail? A 67 X 90 pixel image has so little information that... well, can't you figure it out?

[jagabo]

No matter how high a resolution the sender's camera has, if he sends you a 67x90 picture it will not have much detail. The process of shrinking the image down to 67x90 has thrown away most of the information contained in the original.

An original 640x480 image:


Shrunken to 90x68:


The 90x68 image enlarged back to 640x480:


Here's a simple thought experiment for you: I have a list of four numbers. It's too much to send you so I'll send you only one number, 25. I'll even tell you that that value is the average of my four numbers and the four numbers were within the range of 0 to 255. Can you tell what my original four numbers were? Well, that's essentially what happens when you shrink an image.

[robjv1]

Jagabo -- that's a great little visual for this particular kind of question. I may steal it. People ask me this question all the time and it's always been hard for me to explain it in a way that a novice can easily understand. I often encouage people to use Picassa for their photo needs, because anytime you make a change to a photo in there, it saves the original somewhere else. So if you crop it, size it down, color correct it, and then later decide you want to uncrop it, the program loads up the original.

[Noahtuck]

Or when you work on it, crop it, resize it, ect. save it as a NEW file instead of overwriting the original

This is all such common sense!!
Oop's.. i forget....

[jagabo]

Jagabo -- that's a great little visual for this particular kind of question. I may steal it.

Help yourself!

[coody]

It's understandable the more pixels, the clearer a picture should be. What I try to figure it out is how or why the picture I received by the email is only 67X90 or some pictures on the hosting website have the low pixels. Is it due to the low pixels of the original picture (due to the digital camera’s lower MP) or the pictures have been manually shrunk before emailing or uploading? If it is possible, how many pixels should a picture have at least so that it can be displayed clear enough in a full computer screen? Is it at least 640X480 or more?

[jagabo]

Some email programs automatically shrink images when sending mail.

How big the picture needs to be depends on the size of your monitor and how picky you are. I find 640x480 to be the minimum to get something worth looking at. I chose 640x480 above because it fits conveniently on the page here.

[Noahtuck]

My head is going to implode!!!!!!

[coody]

Some email programs automatically shrink images when sending mail.

How big the picture needs to be depends on the size of your monitor and how picky you are. I find 640x480 to be the minimum to get something worth looking at. I chose 640x480 above because it fits conveniently on the page here.

By the way, what tool did you use to shrink/resize the picture?

[jagabo]

By the way, what tool did you use to shrink/resize the picture?

I used an old version of Ulead PhotoImpact -- 6.0.

[guns1inger]

What does someone emailing thumbnails instead of real photos have to do with video streaming ?