AboutScott Valentine Expertise Most anything about digital post processing (Photoshop, etc), effects, and image restoration, some technical information about digital imaging systems, light and electron microscopy, optical physics and image analysis. I can help with shooting basics, lighting setups, and getting the most out of your digital camera. I am also an 'expert' here for Photoshop (Computers/Technology > Software > Graphics Software > Photoshop).
I am currently writing a book for Adobe Press on composite artwork using Photoshop CS4.
Experience I've been an image analyst and advanced amateur photographer for over 6 years. I run an Adobe user group, focusing on digital media, and have lectured on digital image capture systems. Currently, I am an administrator for a rather large instructional Photoshop forum
Organizations Adobe User Groups, National Association of Photoshop Professionals, Advanced Imaging Specialists
Education/Credentials Bachelor of Physics, University of California, San Diego
Awards and Honors Winner: Best in Show and several category first place awards - Imaging Professionals of the Southwest Print Competition (multiple years)
Expert: Scott Valentine Date: 2/11/2007 Subject: Interpolation
Question Scott,
I want to submit images to picture libraries.However some of them require file sizes of 50MB.I use a Nikon D200 camera which produces images with a file size of 28.7MB these are then edited using photoshop CS2. I can increase my file size from the original 28.7MB to the required 50MB file size by resizing in CS2.
In "image size" I select bicubic smoother, then change the resolution from 240 dpi to 300 dpi and finally in pixel dimensions I select percent rather than pixels and I increase the percentage size to 132 percent which provides a file of 50MB.
Is this the correct procedure or should I buy additional software such as Genuine Fractals and then edit in CS2?
Hope you can advise me, thank you,
Jim
Answer Hi Jim,
These agencies are looking for the best possible image, but most digital cameras don't natively produce files of 50M, as you've discovered.
Your first order of business should be to contact the various agencies and find out how they expect their submissions. Specifically, find out if they have some advice on just how to get to the file size they require, or if they are just using that as a rough guide to actual pixel dimensions.
A few years ago, it was more common to specify file size because most pros were shooting on film and then scanning the negatives or prints. In this cases, the size was determined by how small the sampling points were in the scanner - smaller points meant higher file sizes.
Having said all of this, you are going about things in pretty much the right way. I've used Genuine Fractals with great success, but there is a new game in town; Alien Skin's Blow Up (http://www.alienskin.com/blowup/index.html). I've not used it myself, but the reviews are outstanding. These applications have the advantage of automating the process of interpolation and the associated artifact corrections.
If you do choose to continue doing the enlargements yourself, you should consider taking a step-wise approach to increasing the dimensions. Each individual increase in size should be around 5-10 percent, rather than doing it all at once. Some people say you should sharpen at a few intermediate steps, but you will need to be very careful and experiment a lot with this technique. There are many tutorials online that deal with 'stair-step interpolation'; just do a web search and find one that suits your needs.
One other thing to consider is using Adobe's Camera Raw for processing images shot in RAW (NEF) format. This allows for a large increase in dimensions directly from the original information. You can also choose up to 16-bit color depth (truly only 12-bit, but that's another story). Using RAW will let you perform your basic correction operations as a set of instructions directly attached to the original camera data.
If you have further questions that may be outside the scope of this venue, please consider one of the digital photography or Photoshop-related forums. I am an admin on PhotoshopTechniques.com, which is a great place to get quick responses and ongoing help with specific questions.
