still a bit confused on ppi subject

[mmchenry68]

I am fairly new to digital and trying to understand the best way to save my files.

My question is on large prints. I always shoot in raw and convert to Tiff. With my original Tiff file when I resize and crop the image to 16 by 20 I end up with 178 ppi. My print lab requires 300 ppi for printing images and images have to be sized to print. Would I then just resample and raise the ppi to 300 to send for printing? This makes a huge file size. 82.4M to be exact. If I compress this to a JPEG file on a cd just to send to the lab the file size is just 7.32M. Am I correct in that I won't lose resolution just saving from Tiff to JPEG as long as I don't make any changes to the JPEG file?

I probably won't be printing that many 16x20's but I want to be able to do so. I want to make sure I archive the files in a way that I can produce up to 16x20 if requested but also print smaller sizes as well. I think the answer is to archive the original TIFF file even though this is going to be a challenge space wise. I hate to rely on CD's to archive but my hard disk won't last too long with these file sizes.

I am considering providing clients with cd's so they can do their own reprinting much the same way some photographers only charge for their services and provide the negatives to clients. For those of you who provide cd's to clients so they can have there own reprints made, what ppi and print size do you provide them. Do you provide them JPEG or TIFF?

Sorry if this is a book. I have just learned so much from this forum and if anyone can set me straight I know you can.

Thanks for any advice you can offer.

[Tom Nolle]

What I do for large prints is this:

1--Uncheck "resample image" on the image size dialog and resize the image down to a point where my smallest dimension in the print (16 in a 16x20, for example) matches the image. Be sure to constrain proportions. The DPI will go real high.

2--Crop the image to the print size.

3--check "resample image" and set the dpi to 300.

Tom

[Tom Nolle]

By the way, if your print size is large enough, the dpi you'll get after my first step will be less than 300, meaning that you'll have to interpolate up. If that's the case, after you crop you use Genuine Fractals or Step Interpolation from Fred Miranda, or whatever your favorite interpolator is and get the needed dpi that way.

Tom

[mmchenry68]

Thanks for the info. This is how I have been resizing. I was concerned about interpolating. When I use this technique I end up going from 178ppi to 300ppi for a 16x20. I didn't notice a big difference in quality on my CRT not sure about the printed product. Is the interpolating software you mentioned a plug in to photoshop? I only have Photoshop elements at the moment.

(I am putting away money in my piggy bank for the latest and greatest version of Photoshop. :D)

[Tom Nolle]

Genuine Fractals is a plug-in; I don't know if it works with Elements or not. Fred Miranda's stuff is an action. You could check his website (www.fredmiranda.com) to see if it's compatible with Elements. I think GF's from Lizardtech.

Tom

[Tom V]

Originally posted by mmchenry68
... If I compress this to a JPEG file on a cd just to send to the lab the file size is just 7.32M. Am I correct in that I won't lose resolution just saving from Tiff to JPEG as long as I don't make any changes to the JPEG file?

...the answer is to archive the original TIFF file even though this is going to be a challenge space wise. I hate to rely on CD's to archive but my hard disk won't last too long with these file sizes.

I am considering providing clients with cd's so they can do their own reprinting .... what ppi and print size do you provide them. Do you provide them JPEG or TIFF? ...

If you are going to save the image to CD for a lab to work on, just leave it as a .tif - a CD has plenty of room.

There are two kinds of compression: Lossy and Lossless. Jpg compression is lossy - it throws out data (detail) in order to make the file smaller. Lossless compression makes the file smaller by finding patterns in the data, and reducing it. All detail is retained. TIF files by themselves aren't compressed, but compression can be applied to them. It can be applied in the saving process or after. Lossless compression includes .sit and .zip. While saving the .tif, you may be given the choice to use LZW compression, which is lossless.

A .tif file contains all the data you need on one layer. To save a .tif file as a ,jpg compress the file by deleting detail. Tif files can be compressed without losing detail in various ways: Stuffit .sit, .zip, lzw, etc.

You can open a jpg and close it without any loss of detail, provided you don't change a pixel or the jpg compression setting.

I save my RAW or original images as long as I think they could be useful. I save my layered psd (Photoshop format) documents that I used to build complex images. I save a flattened RGB or CMYK image (without major sharpening) as a working master. I resize and sharpen the working master for each unique instance that it is used. I keep the images on my hard drive if I think I will use them. I also burn a CD-R or two for on-site and off-site backup archives. I frequently burn a CD-R with the images as soon as I copy them from the camera to the hard drive. I think that carefully cared for CDs will outlast a Hard Drive.

I give my clients a CD with the types of files they might find useful. If they are going to be coming back to me for output or to use the image in a advertisment that I will set up, I see no need to give them the highest resolution images. I would give them an automatically generated Web Photo Gallery that Photoshop can make in seconds. If my client is going to repurpose the images in various media that I am not involved with, I give them the images in a basic nearly orginal state. I will weed out the bad exposures, etc., rotate and lightly sharpen the images. I don't worry about PPI or size, because I wouldn't know what PPI or size to make them. If you give them the pixels, they can do whatever they want to them.

[mmchenry68]

Thanks for the reply Tom. This was helpful. I did try saving one of my original TIF files with LZW compression and it was about 1/3 of the original file size. This should help with the archival space issue.

So there is no loss of data if I save the Tif files with lzw compression to archive and then open them and resave as Tif w/no compression if I want to get back to the original uncompresed tif file?

Also, I'm glad to hear you have good results with CD archiving as this is really my only option right now.

Thanks again for the info.