Picture scanning sizes-which?

[621andy]

I've just bought a scanner on Ebay, an Espon 3200 I thnk(on the road at the mo!), and have scanned various old and ancient negatives.

The results are on the whole pretty good, bearing in mind the quality of the negs, the quality of camera at the time and my general bad picture taking:rolleyes:

However, which size should I scan them at? I basically want to save some on my lappy, and also send some to Air Britain etc.

I've tried different 'sizes' and resolutions, but can't seem to get something that matches AIr Britains max size of 500KB, and 1024x768(I thnik).
Basically, when I save a pic and it comes out as a JPEG at for example 1200kb, when I try and shave maybe 1 pixel off an edge, the pic suddenly shrinks to say 60kb. Help!
I've tried scanning at 300pixels,240, and 96, but nothing seems to match up. The scanner gives various options of size, but do I need to scan each neg twice at two different settings, or can I do the same as I do with a digital pic and just change the dimensions:confused:

I'm not explaining this very well, but hopefully someone can understand my ramblings:\

[Bushfiva]

On the assumption you're not scanning for archive, but simply going for "good enough to see/use: colour photos scan well at around 175dpi. You don't gain much more by going higher. Negatives scan well around 2000dpi, you don't get much extra benefit by going to 4000dpi. These would give you the sort of results you would expect from a 6 megapixel camera (very, very approximately).

After that, you might want to use a picture viewer such as Irfanview that will let you rescale images to the size you want to post.

If you're scanning and saving directly as jpeg/jpg, you can choose the "quality" level somewhere in the software. Jpeg is a "lossy" compression system: each time you edit the same picture, unless you are careful, you will lose quality and the picture will get smaller when you save it. With quality=100, the jpegs will be pretty big. 100 is rarely used. Quality=90 is a good place to start, and for posting to the internet you can go down to quality=75 or 60 without too much fuss, and the pictures will be way smaller.

I used to scan to TIFF, and now I scan to DNG. These are lossless formats: you don't lose quality when you edit and save them. Once I've scanned my original file, I simply use Irfanview to create a jpeg of the right size and quality for any particular purpose. The logic is, you can always go down in size and quality to get the final product, but you can't go up: a bad scan is a bad scan no matter what you try to do with it.

The 3200 is a nice choice, by the way.

[bnt]

The way your JPEG file sizes keep fluctuating probably has to do with the JPEG Quality settings in the program you're using to crop them. If the scanner program saved them at e.g. 95%, but the other program saves them at e.g. 80%, that explains the difference.

In general, you should always try to avoid making permanent changes to the original image you scan (or save from a digital camera). It's tantamount to cutting a negative: once it's done, it's done, you can't undo it later. As already noted, JPEG is a lossy format, and the JPEG Quality setting determines how much is permanently discarded. So, archive the original, save any changes in a copy.

The system I have with my digital camera looks something like this:
- I use Picasa (http://picasa.google.com/) to manage the full-size RAW images on the PC, for archival purposes. It does non-destructive editing e.g. when you crop a photo or tweak its colours, it saves the edits without altering the original image.
- I then upload selected photos from there to my Picasa web album for sharing. (I use the Sync facility on "starred" photos in an album, to be specific.) I generally upload the full-size photos to the web album, though you don't have to.
- If I need to embed or send a link to a photo, I can do it from the web page. the website automatically generates smaller images from the larger images you upload, which is fine for web pages.

e.g. the archived original of this photo is 3000x2000, I cropped & resized it in Picasa (for the web album) to 1200x400, and I just told the website to generate a 400-pixel-wide version for embedding here:

http://lh5.ggpht.com/_dsCFvRbv_vo/ROIVjGQaABI/AAAAAAAAAWo/hm2fjWZejQI/s400/03-a380-big.jpg (http://picasaweb.google.com/lh/photo/XB8VHCkifnw1tfE4qo3FVA?feat=directlink)

[Loose rivets]

Just in case you haven't found it:

I'm not sure if you'll have the same menu system, but on mine I always use the professional mode.

At the bottom, you'll find a small button as part of the SCAN button. That gives FILE SAVE SETTINGS.

It's odd, but in there, they put another sub menu in JPEG OPTIONS. That's where they put the compression level.


I have to confess that I save most stuff in JPEG, but archive at typically 1.2m file size for small photos. I then use freebie Fast Stone Photo Resizer for a quick change to e-mail or Pprune sizes. I think about 170k file size fits a Pprune screen just about spot on. But don't quote me on that.
It's very fast, and you can do a whole batch at a time...changing by a RATIO or to specific sizes etc..

Just one of the goodies recommended by this forum.:ok:

[621andy]

Many thanks everyone:D

I've also just worked out in PS Elelments there's an option to 'save for web' which seems to do the job- dunno why I didn't find it earlier:rolleyes::}

[airborne_artist]

FWIW most colour glossy magazines print at 1200 dpi, so there is no point going higher if scanning a positive. The difference between 600 and 1200 is not that much in real life, and results in a file 25% of the size.

A really good quality gloss photo print from a pro-quality slow film is probably about 4000 dpi.