One would think that resizing an image would be easy. I've always had a grasp on this and never thought about it much until last night's workshop that I taught. I wanted to show examples on both the MAC and the PC.
On the PC I showed how to use Paint, How to Right Click in File Explorer and use the Send by Mail and I showed how to do it using Lightroom. Now I've always used Lightroom since version 1 and its so easy now with the Custom Export jobs you can save. I have custom jobs for 1024x768 at 72 dpi JPG, 1920x1080 at 72 dpi JPG and 2048-by-1536 (yes an odd size but its what my iPad uses (at 264 ppi)). Because I use these save Export jobs or presets, I never give it much thought. But after some questions yesterday and some e-mails that followed, I released perhaps it's a little tougher that I thought, specially for people new to photography and DPI, Resolution, Sizes, Colorspace and so on.
At club (Delta Photo Club) we use a full HD capable projector and display images at 1920x1080. CAPA used to have an old archaic standard for years at 1024x768 which many clubs still use today because they never updated their projectors because CAPA never demanded more. But, thankfully CAPA changed their standard to 1400x1050. Note that I could not find mention of this on their website and under their 2014 Digital Competition guidelines it still stated as 1024x768. But I have been told its 1400x1050. This is an odd size for digital display as most projectors are capable of much higher resolution. Of note is that this size is a 4:3 aspect ratio which is in keeping with older standards for photography and one that is till used today in Micro 4/3 cameras and most pocket cameras. Why they would choose to support those standards as opposed to most photography enthusiasts 3:2 aspect ratios found in most DSLRs, I do not understand. Note also that OLD monitors were also 4:3 aspect ratios but you cannot even buy those anymore. Most monitors now use a much wider aspect ratio.
A challenge of course is that Vertical images must always display smaller that horizontal images because of the vertical pixel limitations. An actual 1400x1050 horizontal image would become 787x1050. No fair for those entering Vertical images. In print the images can be 16"x20" Vertical or Horizontal. Perhaps a better option would have been to use the full height of an HD projector as limits, thus making images 1080x1080 as the max size. A 1:1 aspect ratio.
Another thought would be to limit the total number of pixels or total number of square inches. This could add a fairness to those submitting panoramic images. But I digress...
So for Digital Image Submission here is what is required
SIZE (In Pixels): 1024x768 or 1400x1050 or 1920x1080
Dots Per Inch (DPI): 72 (more on this below)
File Type: JPG
Delta Photo Club is 1920x1080
CAPA is 1400x1050
Some competitions (read the rules) are 1024x768
So you can quickly see what problems lie ahead here. When clubs ask for image sizes they want the size in pixels but they also require 72 dpi using the sRGB colorspace. Most beginners do not know this and worse they do not even know or understand what it is. Most digital cameras now shoot RAW and so conversions are required. Also, most beginners quickly learn that using AdobeRGB or ProRGB are better color spaces for photographers that print images. Lastly most digital cameras do not shoot at 72 dpi as a standard and most printers want 240 or 300 dpi images.
So, most of these settings all need to be changed when resizing images for club or competition.
Programs like Adobe Lightroom and Photoshop easily handle these changes when exporting images. Doing this on a MAC or PC using built in tools is either more complicated or not doable at all.
I remembered that Microsoft had a great FREE app just for doing this that was part of the Windows XP Power Toys package. I grabbed a copy and found that this program will not run* (perhaps it runs but it does not install) in a Windows 7 or 8 machine. So I downloaded several apps to do this. I found they were all lacking and many were trouble navigating to a ?safe? download area. I encountered several threat/virus issues along the way. So I would NOT recommend blindly looking for and installing several apps to do this.
I do on occasion use FaststoneViewer on my laptop and it has a separate Resize tool. This tool will handle it all but it is fairly complex to use and most beginners would have a very hard time getting the correct results.
So I turn back to Lightroom. Besides being one of the best and easiest to use tools for editing and organizing images, it?s also a great deal at $159.99 cdn (often on sale for less). Or you can opt for a subscription to Adobe Creative Cloud Photography Edition where you get Adobe Lightroom and ALL updates and Adobe Photoshop and ALL updates for only 9.99 per month. A great deal.
I never did have the time to do the conversion on the MAC and so I will explore it further. The MAC will change settings when emailing depending what mail program you use, but again, the results may be different. Again, Lightroom is a great MAC solution also specially since Apple has laid Aperture to rest.
So watch and check your images once you have resized them or exported them. Look at the Metadata in the image to see if its correct. Some of the utilities change sizes but do not change colorspace unless you specify JPG. Also, many will not change the DPI settings.
So perhaps someone out there knows of a great free utility that will do this for a PC and for a MAC. If you do, please let me know.
Why 72 is significant
(This section is from somewhere on the web and was part of my archives. The link no longer worked. I will try to find the original source.)
Many file formats, including JPG, TIF and PSD, store an image's pixel density setting. If you save a JPG at 200 pixels/inch, it will remain at 200.
Other formats, including GIF and PNG, discard pixel density. If you save a 200 DPI image as a PNG, it won't save that DPI at all. Many image editors, including Adobe Photoshop, assume that an image is 72 DPI if the information is not stored. (Note: Photoshop's "Save for Web" feature discards unnecessary print information, including pixels/inch from its Image Size dialog box.)
Seventy-two is a magic number in printing and typography. In 1737 Pierre Fournier used units called cicero's to measure type. Six cicero's were 0.998 inches.
Around 1770, Francois-Ambroise Didot used slightly larger cicero's to fit the standard French "foot." Didot's pica was 0.1776 inches long and divided evenly into 12 increments. Today we call them points.
In 1886, the American Point System established a "pica" as being 0.166 inches. Six of these are 0.996 inches.
None of the units ever strayed far from 12 points per pica: 6 picas per inch = 72 points per inch. It was an important standard by 1984, when Apple prepared to introduce the first Macintosh computer. The Mac's interface was designed to help people relate the computer to the physical world. Software engineers used the metaphor of a desk to describe the arcane workings of a computer, right down to "paper", "folder" and "trash" icons.
Each pixel on the original Mac's 9-inch (diagonal) and 512 x 342 pixel screen measured exactly 1 x 1 point. Hold a ruler to the glass, and you'd see that 72 pixels would actually fill 1 inch. This way, if you printed an image or piece of text and held it next to the screen, both the image and hard copy would be the same size.
But early digital pictures were clunky and jagged. As screen technology and memory improved, computers were able to display more pixels on the same size monitor. Matching a print-out to the screen became even less certain when raster and vector apps allowed users to zoom in and examine pixels closely. By the mid-1990s, Microsoft Windows could switch between 72 and 96 pixels per inch on screen. This made smaller font sizes more legible because more pixels were available per point size.
Today, designers and clients alike understand that the sizes of items on the screen are not absolute. Differences in screen size and zoom functionality are commonplace. But 72 is still the default.
The Reason for 72 dpi
Besides being "the" standard, clubs and organizations also want to make their own lives easier. Some programs will display relative sizes versus actual sizes. So a 1" by 1" image at 72 dpi and a 1" by 1" image at 144 dpi should both display and print the same size but this is not always the case. By specifying a standard there is less chance for problems with sizing to occur. 99 percent of the time having the wrong dpi setting will be ok but note that many competition boards will not accept images that have not been correctly formatted!
I will continue to work on a document that explains all this as clearly as possible and will look for good simple solutions for both the PC and the MAC. Will keep you posted.
© 2014 Francois
Version 1.00 - October