editing a jpeg

[patriciaann]

I am in a camera club which has a lot of members that use point and shoot cameras, a lot of these cams do not shoot in raw and we are finding that the members do not understand about jpegs and how they lose data when being edited and cropped.
I would like some advice on what might be a good format to resave the file that is losless but wont blow the file up beyond its capability of printing a decent A4 image. They are cropping their shot then blowing them up to A4 and they look almost pixelated and very soft, no sharpness at all, and otherwise good images are being ruined, can they only ever be printed to 5 x7 or is it possible to get them to A4.

[kiwi]

i guess it depends on the size of the file to start with, A lot of P%S camears have as many megapixels (10+) as a SLR so cropping and printing ought not to be a problem. It may be more of an issue on how much they are cropping and how they are resizing/preparing for print which is no different than a RAW file really.

[ameerat42]

When they're "blowing them up to A4" (at least not C4) how are they doing it?
Are they resampling the image (ie, adding pixels and increasing the file size again), or are they just cropping the original and printing it at that size (A4)?
What programs are they using to do it?

About lossless saving...
You can save as a TIFF, which is lossless and can still be compressed to about half the normal file size (using the LZW option). I don't bother with compressing tiffs as I've got plenty of HDD space.
TIFF is a recognised format on most printing outlet machines.

If you must re-save as jpeg use the highest quality setting (File - Save As..., and level 12 jpeg quality in Photoshop). If you use the Save command you are just overwriting the current file and degrading its quality each time.
Am.

[Keith Young]

Hi patriciaann, I suppose the idea with a camera club is to share experiences, ideas, technique, and of course what gear you use. I suppose that when these other members see the results you are getting with a DSLR, some nice glass and shooting in raw, they will soon discover that the method/gear they are using has its limitations. All you can do is advise them in the nicest possible way.

Enlarging an image from a limited number of pixels is generally going to end in a poor result.

What I see is that if they are cropping too much they need a bigger lens (camera) or need to get closer to get a better result. Even if you crop a high mega-pixel DSLR shot too much it will eventually pixelate. If the jpg compression is too high in camera, the "jpg artifacts" will show up sooner than with a raw file this is the other battle you have on your hands. When you crop, or shoot in jpg, you are throwing away data/info that you may have wanted at a later date. Just make sure they never crop the original, make a copy first I guess.

All I can suggest is smaller prints and don't crop so much.

However there is a Photoshop plug-in called "Genuine Fractals", it claims to be able to enlarge images to up to 10x their original size. I've never needed to use it and I don't know what it would do with the type of images you are dealing with.

[OzzieTraveller]

G'day patricia

There are several things here that come to my mind - some have been mentioned above...
Another is 'magnification factor' in printing these images ~ something that is very rarely discussed in the photo media [stuck as they are simply on megapixels]

You state that "a lot of members that use point and shoot cameras" - but these can fall into several categories [even an SLR in auto mode is a glorified point-'n-shoot]. However, lots also comes down to the sensor size in millimetres vs the print size in millimetres/inches

for example
an SLR sensor is about 17mm x 24mm and to print it to a 14inch x 20inch photo is 20x enlargement
However
a slip-in-the-pocket p&s sensor is about 4mm x 6mm, therefore a 20x print is 4" x 6"
and a superzoom sensor is about 6mm x 8mm, and its 20x print would be 5" x 7"

So ... if the lens is up to it, and there is no camera shake, and if the focus is ok ... then a 20x print should hold lots of sharpness
But - if any of the above are 'out' then that problem is magnified too greatly, and becomes very visible on the print

To take a superzoom sensor of 6mm x 8mm [for example] and print off an 11" x 14" print becomes a 40x enlargement ... and you / the photographer has to get everything 'just-right' for it to succeed. At 40x enlargement, any camera shake / focus inaccuracy etc will make the image "soft"

Hope this helps a bit
Regards, Phil

[ameerat42]

Quite troo, too, Ozzie! It is a rare topic indeed these digital days. I remember when for a serious portrait you'd be looking to medium format... (and so on...)
I'm just wondering if pixel density does not have some mitigating effect on the degradation due to magnification?
Am.

[OzzieTraveller]

G'day am

good Q to ponder upon ~ maybe a topic in its own right
I realise that it's possible to print anything to any size - replace each pixel with a 4" paint brush and you can end up with something that's "real big mate"

However, to maintain good image quality, I feel that there must (??) be some physical upper limit as to where you can go before the image starts to fall away
But that still presumes that there is absolute focus accuracy, no camera or sublect movement etc etc ~ cos if there is, a 40x magnification for printing will produce some awful looking results

Maybe Arthur the technical expert at lots of stuff can offer his 2-bob's worth
Regards, Phil

[peterb666]

Well I use to use a 3mp point and shoot and print at A4. They looked pretty good.

There is a limit to cropping and the smaller the sensor and the lower the resoution is going to be limiting (not that high resolution small sensors are any better as the images are generally mush to start with).

There are ways that you can limit damage but if your folks don't understand cropping and the limits they are unlikly to have the skills or want to put in the money to do it.

If stuck with a jpg image, the first thing I would do is convert it to a 16bit TIFF with no compresion. You won't gain any colour info from converting to 16-bit colour but if you are going to play with white balance or anything else that affects colour it may help.

Next I would load the image into something like Adobe Camera RAW. The beauty of this is that you can make a whole series of changes but it isn't until you use the Save Image option, which is essentially an export option, that you muck about with the image. Camera RAW creates a seperate file to hold the adjustment data and it is applied in a single opertion. It is at the Save Image export process that you return the output to jpeg. Use the automatic or optimised compression setting and the software will normally do a good job of reducing file size without losing quality.

The key to getting a good image out of a point and shoot camera that only provides jpegs is to get the image right in the camera. That means the right exposure, the right colour balance, the right focus, the right framing (if possible).