On Tue, 3 Mar 2009 21:16:40 +0100 (CET), A. M. wrote:

When I take my 35mm film roll in to my local photo lab for developing, I get a set of prints on CD. Can they print a 5 x 7 inch enlargement of one of these CD prints after I have made some changes with GIMP, or will they only be able to make a print from the negative (which I can't make changes to)?

Most photo labs nowadays can print photos from digital sources - after all, film is quickly becoming obsolete.

When I take my 35mm film roll in to my local photo lab for developing, I get a set of prints on CD. Can they print a 5 x 7 inch enlargement of one of these CD prints after I have made some changes with GIMP, or will they only be able to make a print from the negative (which I can't make changes to)?

There should be no problem in getting a print but I suggest you ask them first to find out what they require the Gimp image to be saved on.

Norman

On Wed, Mar 4, 2009 at 2:47 PM, A. M. wrote:

OK, thanks.
I just wondered if the CD photos would have the right information - I read somewhere that the ppi. for photo printing should be about 200, the ppi. for my CD prints is 72.

It depends on the pixel dimensions - if the CD photos are only 360 px by 504 px ( which is 5"x7" at 72 DPI), you will not get very high quality prints. However, I suspect the CD photos are probably much larger - so you should resize them to 5x7 with software like GIMP and see what the resulting PPI is... Wow, does that even make sense?

Let me try again: even though the CD photos are at 72 DPI, they're probably much larger than 5x7 - if so you can resize them to 5x7 and end up with a higher PPI.

Most drugstore labs (where I live) can print photos from a SD card or a USB stick...

Chris

A. M. wrote:

OK, thanks.
I just wondered if the CD photos would have the right information - I read somewhere that the ppi. for photo printing should be about 200, the ppi. for my CD prints is 72.

You might enquire of the place you take your film for processing whether you can specify the PPI of the processed images, in which case I would specify a ppi of 300 or more. If you cannot, and you have a scanner, you might be able to scan the negative on your scanner, and "develop" which would be basically changing to the color balance of the image and prepare the images at home. I have had reasonably good luck scanning both positive and negative images made on 35 mm film in a variety of media on a flatbed scanner, and processing the film. I scan at 1200 dpi, and by printing at the same image 300 dpi, I increase the size of the printed image by 4 times.

ns

It depends on the pixel dimensions - if the CD photos are only 360 px by 504 px ( which is 5"x7" at 72 DPI), you will not get very high quality prints.  However, I suspect the CD photos are probably much larger - so you should resize them to 5x7 with software like GIMP and see what the resulting PPI is...  Wow, does that even make sense?

Let me try again: even though the CD photos are at 72 DPI, they're probably much larger than 5x7 - if so you can resize them to 5x7 and end up with a higher PPI.

Most drugstore labs (where I live) can print photos from a SD card or a USB stick...

Actually, the DPI is adjusted on the fly in the shops that I am familiar with. You take a digital image of any dimensions, tell them on what size to print it, and that's it. Naturally, trying to print 320x240 px image on an A4 sized print will look terrible, but up to the technical limits of the machine it can be done. Therefore, make sure that the shop that gives you the disc used a high (at least 300 DPI, and 1200 would not be unreasonable) resolution setting so that the resultant prints will look decent.

A.M. -

This has wandered a bit, but here's some of my experience - FWIW.

The classic PhotoCD may have one or several resolution scans of each photo. I have had pretty good results to _at_least_ 6in.X4in. by resizing the digital image to a print resolution and image size I wanted, but I did find the moderate sharpening improved it. (This was for my home printing.)

Here in Atlanta, GA, USA, we have many consumer-oriented develop-and-scan labs that can give you a decent PhotoCD. Chances are that's what you got. These places don't always know much about printing nor can they give your work personal attention. We have much better luck by taking the CD to a "pro-sumer" photo store where they can do a bit more careful printing - and maybe have a look beforehand at the images to guess how well they might print. I suggest you find such a shop and have a few images printed, now that you have the CD and can go back if you are happy (or _unhappy_ - they may be able to try some adjustments).

In particular, ask them whether the PhotoCD already has images of adequate resolution for the print size you want. I've heard 200 - 300 dpi as good values (at your final print size), and my experience has borne this out. The old darkroom standard of an 0.01 in. "circle of confusion" on the print is 2-3 times coarser. The depth of field scales on most 35mm camera lenses were about 1/500 in. circle of confusion at the film, or about 500x750 pixels in the whole negative or slide. This wasn't really sharp enough to print over 4x6 in. (not for me anyway), but at least gives you a point of scale to think about.

Naturally there are professional processing houses in most medium-sized and larger cities, but those services are much more expensive and may not be so useful until you are a bit more experienced with prints from a mid-range shop.

Anyway, take your time and expect a few rounds (or maybe lots!) of experiments before you get results that consistently please you, just like in film photography. You'll probably find yourself thinking about light, color, composition, ..., before you run out of pixels.

If you have good internet access, do some searches with your favorite engine and you will find _LOTS_ of good work samples, tutorials and discussions. Ditto for visiting your library.

GIMP is a useful and well-organized tool. It's well worth playing with your images and trying lots of variations. Hey, you can't break anything!

Best regards and happy shooting.

- John Mills

On Wed, 4 Mar 2009, A. M. wrote:

You might enquire of the place you take your film for processing whether you can specify the PPI of the processed images, in which case I would specify a ppi of 300 or more. If you cannot, and you have a scanner, you might be able to scan the negative on your scanner, and "develop" which would be basically changing to the color balance of the image and prepare the images at home. I have had reasonably good luck scanning both positive and negative images made on 35 mm film in a variety of media on a flatbed scanner, and processing the film. I scan at 1200 dpi, and by printing at the same image 300 dpi, I increase the size of the printed image by 4 times.

ns

That's very helpful. I think my local computer repair shop has a scanner, so I'll try that.
Thanks very much.

All -

Sorry - I checked and found I was wrong on several points here:

1. Most significantly, I don't have any example of a "strict" Kodak PhotoCD to even test. I have three CDs from three processors and they all have just JPEG images (plus viewers, ads, etc.). Those images are about 1200x1800 pixels, or about 9x6 in. at 200ppi. Easily viewed with GIMP, however.

2. "Real" PhotoCD format in principle offers several image resolutions up to much higher than that, but generally requires a viewer or plug-in. I got mixed results as to what versions of Photoshop or Photoshop Elements can unpack the Kodak formats, either natively or with a plugin.

3. I found a library (libpcd) and viewer (xpcd) that are free, have versions for Linux and (I believe) Windows equivalents, and do mention a plug-in for GIMP; I did not come up with the plug-in, however. I found the links at:
http://dl.bytesex.org/releases/libpcd/ http://linux.bytesex.org/fbida/xpcd.html

Thanks for your patience. I at least learned something from the experience.

- John Mills

On Tue, 3 Mar 2009, John Mills wrote:

The classic PhotoCD may have one or several resolution scans of each photo. I have had pretty good results to _at_least_ 6in.X4in. by resizing the digital image to a print resolution and image size I wanted, but I did find the moderate sharpening improved it. (This was for my home printing.)

Here in Atlanta, GA, USA, we have many consumer-oriented develop-and-scan labs that can give you a decent PhotoCD. Chances are that's what you got. These places don't always know much about printing nor can they give your work personal attention. We have much better luck by taking the CD to a "pro-sumer" photo store where they can do a bit more careful printing - and maybe have a look beforehand at the images to guess how well they might print. I suggest you find such a shop and have a few images printed, now that you have the CD and can go back if you are happy (or _unhappy_ - they may be able to try some adjustments).

In particular, ask them whether the PhotoCD already has images of adequate resolution for the print size you want. I've heard 200 - 300 dpi as good values (at your final print size), and my experience has borne this out. The old darkroom standard of an 0.01 in. "circle of confusion" on the print is 2-3 times coarser. The depth of field scales on most 35mm camera lenses were about 1/500 in. circle of confusion at the film, or about 500x750 pixels in the whole negative or slide. This wasn't really sharp enough to print over 4x6 in. (not for me anyway), but at least gives you a point of scale to think about.