Message-Id: <mailto:199507261421.JAA23149@library.wustl.edu> Date: Wed, 26 Jul 1995 10:16:59 +0400 From: Terry Lund <mailto:lund@PCD.KODAK.COM> Subject: Re: Advice requested for scanning to PhotoCD To: Multiple recipients of list IMAGELIB
Somehow I managed to quote the wrong pixel resolutions for Photo CD in my attached post. I realized my mistake when I read Walter Gilbert's excellent response to the initial post by Mia Massicotte.Sorry for any confusion my error may have generated :-(
I edited the attached copy (the lines without any ">" to correct my mistake(s).
-Terry
At 3:06 PM 7/25/95, Terry Lund wrote: >Mia,
>
>You might want to check out the sample digital image area on Kodak's web
>server. The page at:
>
>http://www.kodak.com/digitalImages/samples/aboutPix.shtml
>
>describes how we started with Photo CD images and generated the sample
>images shown in that section of the Kodak Web Server. This doesn't address
>your questions directly, but does illustrate what can be done starting with
>Photo CD images. I added other comments to your individual questions, and
>I hope this helps.
>
> -Terry Lund
>
>At 10:52 AM 7/25/95, Mia Massicotte wrote:
>
>>We have had a professional photographer take some shots of our library for
>>a virtual tour project that I'm putting together. I want him to put the
>>images on a PhotoCD, which I will later manipulate on a Mac with
>>Photoshop, and mount them on our Mac webserver. I would like one high
>>quality archival image for posterity, one image at 72 dpi for the
>>webserver and subsequent screen viewing, and one thumbnail.
>>
>>
>>My questions are:
>>
>>1a. For the image at 72 dpi, I don't want to have to resize or crop these
>>images when I place them into my web pages. I think l want the images to
>>be approx 4" h x 5 inches wide when displayed on a monitor. I've been told
>>I need to specify to the lab that something called the 'aspect ratio'
>>should be 4x5 for 35 mm film. This should result in an on-screen image of
>>300 w by 200 h pixels. Is my information correct?
>
>Assuming you are scanning from 35mm film, the original film image is about
>24mm by 36 mm size (aspect ratio is 1 to 1.5). This means you cannot get an
>image 4" by 5" (aspect ratio is 1 to 1.2) without introducing distortion in
>one direction or the other. You can have 4" by 6" or you can have 2.5" by
>5" by interpolating the image data.
>
Photo CD images have five resolutions "built-in", for scans from 35mm film. The resolution called BASE/4 will be 256 by 384 pixels, which is pretty close to what you wanted. >
>>
>>1b. If I want the 72 dpi images instead to display on screen (without
>>cropping) at a size of say, 3" high by 4" wide, how should I specify this
>>to the lab making the CD?
>
>From the above comment, the BASE/4 image will be about 3.5" by 5.33" at 72 dpi
on a monitor. >
>>
>>2. For the 72 dpi image, I assume that the image would be in PICT format
>>on the CD. If I then convert the 72 dpi image to jpeg for my web project,
>>will this result in too great a loss of quality? Should I try to convert
>>the archival image to a 72 dpi jpeg instead? Any suggestions?
>
>No, the image is not in PICT format on the Photo CD disk. Follow the notes
>from the Kodak web page referenced above to see how we converted from Photo
>CD files directly to GIF or JPEG for the web.
>
>>
>>3. Initially, I used Apple's QuickTake digital camera for some quick and
>>dirty prototyping. I noticed that displaying the photos (I had converted
>>from pict to gif for the test) on Mac monitors (475's, 575's, Powermacs)
>>looked acceptable; but on PC monitors were way too dark. Is this darkness
>>a function of the PC monitor's capability, or did it have more to do with
>>the gif compression? Will I run into a similar problem with my jpeg
>>images, and if so, can it be avoided?
>
>This gets complicated (and can be messy) because monitors can be setup to
>almost any set of conditions, and the viewing conditions also impact the
>apparent darkness of images displayed on different systems. The only way
>to be sure of the results is to have some type of color management software
>running on the different computers, and to have the viewing conditions
>controlled (limit the amount of stray lite on the screen, and have somewhat
>subdued lighting).
>
>>
>>The bottom line is that I want the highest quality image that I can get
>>from the original, to mount on my Mac webserver, for monitor display at 72
>>dpi, with an on-screen size of about 300 pixels wide by 200 pixels high.
>
>When you start with digital capture (as in #3 above), you have to worry
>about the camera color calibration, as well as any of the processing
>software formatting the images, as well as color management for the browers
>displaying the images. At least if you start with Photo CD images, you
>have image data that is in a well defined color space.
>
Terry Lund Phone: 716-588-6855 Eastman Kodak Company FAX: 716-477-1498 1999 Lake Avenue KNET/KMX: 258-6855 Rochester, NY 14650-2210 Internal Mail: 7/83//RL/02210