View Full Version : Digital Photographs

tony draper
1st Sep 2008, 10:53
Summat puzzles me about em,Sis was up here last week pointing her Digital camera everywhere,they emailed me some pickies last night,most of em showing in properties to be betwixt 50kb to a 100kb except a couple showing as being over 5 Mb,the afore mentioned ones were a doddle to download,the last couple took ages to download from the email server what with one being on dial up, however ,the small caliber ones show very little difference in terms of quality resolution or sharpness than the ones that take up all those Mbs,so what is the score here?

1st Sep 2008, 11:22
The main reason is down to the resolution of the image. Native images, ie straight from the camera at the highest quality setting will produce the 5mb images. When the image is reduced either by decreasing the actual size or by reducing the resolution ie the number of pixels in the image, then the file size drops. Computer monitors (CRTs - not sure about flat screens) normally only display a limited resolution of 72 dpi (dots per inch) therefore any resolution higher than that will not show up as a better quality image.

A very basic explanation and I'm sure someone will provide a more accurate explanation, but this one will do for starters!


1st Sep 2008, 11:24
There won't be any difference with the larger files (more Mbs) because the best resolution you can get depends on the resolution of your monitor. If you took a 4Mb image from my camera and an 18Mb file from something like a Hasselblad, the resolution would be identical on your monitor. Because of that, you can always reduce your file size before sending pix to people because the higher resolution images don't look any different ... unless you want to print them out of course.

Loose rivets
1st Sep 2008, 11:57
Try putting box/marquee round a given area, then make that full screen. Do several tests like that and you will see when they start to pixelate sp? The ratio between the area of the full picture and the boxed area ( just before they turn fuzzy with pixels,) gives a rough idea of the useful amount of expanding they will tolerate. So a 5mb might give a useful picture from a very small picked box.

Going back to your T/V days...er, that's if you have to go back to them...you will recall the picture being defined with vertical lines. Aint no such thing of course, but they are representative of the amount there would be based on the horizontal lines. Well, I know what I mean.:uhoh:

When I got my Nikon, it was a modest 6 ish mp compated to the Canon's 8. The pundit's all spelled out the picture was equivilent to the vertical lines, and not to worry too much about product of vertical X horizontal lines.

1st Sep 2008, 12:01
Different rates of compression perhaps, tony?

The difference is not easy to spot with the naked eye in JPEG compression unless you lay the images on top of each other and alt+tab between the windows.

The way you've mentioned it, looks like the former are compressed, the latter are not.

1st Sep 2008, 12:07
Or zoom/crop them on your PC BlueD....

i.e. one taken with a higher MP camera (eg my 10mp compact vice the 2 mp one on my phone) contains more detail, even if they may look the same when viewed at a size of 6 inches wide on my PC monitor. If I zoom in on that 6in wide photo, the 2mp one immediately looks blocky, whereas on the 10mp I can zoom in to my heart's content...

Worth noting!

Loose rivets
1st Sep 2008, 14:47
Mmmm...Okay, but you should be comparing like for like. The size of the array is all important, and sometimes the simple comparison...er, simply isn't.

The lens on the phone just can not replicate even a moderate lens on a SLR for example. Having said this, One is often astonished at the result of such a mini-camera.

I think the substance in the head-bone has a lot to do with the the final result.

The large array will of course allow (the designers to effect) the transfer of more data in a given time.

One would dearly love one of the new "full size" array cameras. Just a teeeeeeeeenzy bit pricey yet awhile.

tony draper
1st Sep 2008, 15:28
Bah! one shall stick wi me Box Brownie, :rolleyes:

1st Sep 2008, 15:59
The lens on the phone just can not replicate even a moderate lens on a SLR for example. Having said this, One is often astonished at the result of such a mini-camera.What about pinhole cameras then?

Loose rivets
3rd Sep 2008, 06:36
There has to be a funny answer to that...give me time :}