Image Editing question

[Duszolap]

First i am gonna say hello beacause i am newbie on this forum. I am not readin this forum for long but i found it really interesting so far. About 4 month ago i bought my long awaited G2 and started to get knowledge about photography at all. so i have some questions :)
1)First sad news - i found some hot/dead pixels on series of my photos - they seem to appear in the same place (i found one to be exact:) - Because it photos were shot at night/dark room thos bad pixels are rather frustrating. I noticed that this topic was discuted few posts ago. From what i see i will have to edit those pictures to remove hot pixels. What i dont like is:
-time consuming :)
-i will loose all info about photo (shutter speed etc) after editing with PSP or so
-i will loose quality? - and thats rather question for you. As far i know PSP or simlilar software while saving edited image compress it again - so if i am not mistaken compressed image is compressed again - for me its equal to loosing quality - am i wrong?
If i am not - is there any way to avoid it? Hot/dead pixel problem is pushing me to edit image but if its possible to edit and still maintain source quality please tell me how:).
Sorry for this long story above but i am cuorius person and i have one more question.
2)I am taking photos at 2272x1704 resolution. I would like to print is as normal photo (not on printer but at photo studio like conventional photos). What maximum size of photography while still not having visible pixels can i have with mentioned above resolution. I am not expert and i really dont know how translate pixel measured size to conventional photography size ( i feel it have something to do with DPI stuff:)
Thats all.
PS. I hope its understandable.If not - soorry for my english - my native language is polish btw.

[jmhobbs]

Hi Dusz,

I can answer a couple of your questions. Regarding your hot/dead pixel issue, you mention that you saw it on pictures taken at night or in a dark room. This is pretty typical of digital cameras. Even the more expensive pro models have this issue. The darkness requires the shutter to be open a long time, as well as the sensor to be sensing for a long time. Aparently that causes some pixels to litterally get hot. If the air temperature is cool, the problem is less likely to occur.

As far as losing quality while editing your photos, use the TIFF format as much as possible. TIFF is a loss-less format, so no quality is lost. Shoot your pictures in Raw mode, then convert them to TIFF's. Leave your pictures in TIFF format as long as possible. Most digital labs can print TIFF's so you shouldn't ever have to save the picture in any other format. This will greatly reduce the loss of quality while editing. If you convert to JPEG, GIF or other compressed format, then your pictures will lose quality when you save them.

Most professional digital labs will print at 300 dpi. Some are doing 400 dpi. So if you shoot at 2272 x 1704 you should be able to print up to 5x7 without any resampling issues (2272 / 300 = 7.57 inches, 1704 / 300 = 5.68 inches). I've printed a number 8x10's from my G2 and they look awesome. I'd say you could go to 11x14 without significant quality issues.

Jon

[PatrickEggers]

Hmmm...would changing the ISO rating help with "hot" pixels? I'll have to do some experimentation...

[jmhobbs]

Patrick,

Changing the ISO would help in that it would shorten the amount of time that the shutter is open and the sensor is "sensing". The problem is that the sensor gets hot (litererally) during long exposures. The sensor is an electronic chip, much like a Pentium CPU, which gets hot with use. The longer its "turned on", the hotter it gets (no double entendre intended :))

The down-side of changing the ISO to get a faster shutter speed is that the amount of noise in the image would increase. Ultimately, it may be easier to deal with a couple hot pixels than the extra noise from a high ISO.

Another option is to only shoot at the North Pole :)

Jon

[leony]

You'll notice tha "hot pixels" migrate from time to time. This is because they aren't damaged pixels - just ones that get hot. On the issue of noise:
fredmiranda.com sells an action to elliminate noise in the PhotoShop, well worth it - click on "Actions" and then look for G2's section. If you don't want to pay anything, use PhotoShop's "Dust & Scratch Removal" filter - it does a half decent job with noise. Of course you can make your own action from a combination of layers with different degrees of Smart Blurr, Edges and Sharpening. I bought the action from FM and am verry happy with it.

Hope this helps.