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Tip: A Free Resolution Chart and a Guide to Image Resolution
I recently did a presentation about inkjet printing and made available a “Resolution Chart” PDF which I created over 10 years ago. It’s nothing fancy, but I’ve found that the chart often helps people to better understand how file sizes change as PPI or file dimensions increase or decrease. It can also help to quickly determine the file size you need when ordering scans, or when making your own scans.
A cropped section of the Resolution Chart.
HOW TO GET THE CHART
A link to the resolution chart, along with 12 inkjet tips (one a week for 12 weeks), will be sent to you by subscribing to my Inkjet & Imaging Tips Newsletter, which is a free newsletter sent periodically with tips, information about gallery shows and workshops, as well as info about imaging related products and offers that I believe are valuable to readers. It’s not a newsgroup, so you won’t be sent messages by others–only I post to it, and it arrives in your in-box like most e-mail newsletters. The box to subscribe is below, or you can enter your e-mail in the form on the right-hand side of this website.
When you confirm your subscription, you’ll be directed to a landing page with two links-just copy and paste each link into any browser to see the 10 tips and to download the chart.
HOW TO USE THE CHART
After downloading the chart, you will see a series of numbers. Along the Y-axis (along the left side) are common film and image sizes (File Dimensions). Along the X-axis (across the top) are various PPI (pixels per inch) numbers, as well as some RES numbers. RES30, RES40 stands for Pixels Per Millimeter, and the term is often used by companies who make continuous-tone transparencies and negatives. (Just multiply the ppm (or RES number) times 25.4 to get the equivalent PPI).
To determine file size for a specific dimension and resolution (PPI), just choose a dimension, such as 11×14 inches, and follow the line across from 100-2032PPI to see how the file size changes (this assumes an 8-bit RGB file in TIFF format with no compression or extra layers). A grayscale file would be one-third the size since it has one instead of three channels. A CMYK file would be four times the grayscale file’s size because it has 4 channels.
HOW DO I KNOW WHAT RESOLUTION TO USE?
The question of what PPI at what size is always a question that comes up. I always say “test, test, and then test again!” to see what works for your images. I print most of my work around 300PPI at final size to inkjet printers and continuous tone photo machines (like those found at Pro Labs, or drugstores). However, 180-200PPI or even lower has been fine for me in most cases, especially when making larger prints. Your file’s image quality, plus the paper, printer and final output size all contribute to the final quality of your prints.
It’s quite amazing how relatively small files can make outstanding prints, especially if they are not over or under-sharpened or have artifacts (common with JPG files that have been compressed, or with lower-quality cameras). It’s also amazing to me how two different papers output on the same printer can show a very different level of visual sharpness.
DETERMINING FILE SIZE IN AN IMAGING PROGRAM
You can check just about any file size quickly in a variety of imaging programs. Below, I show the File>New dialog box for Adobe Photoshop. Just enter the dimensions, PPI and Color Mode (for example, Grayscale, RGB, etc) and you will see your file size appear at the top of the box.
If you are an educator and would like to make copies of this chart for your students, please contact me, and I will review your request. I’ve seen many of my students truly understand for the first time the concept of resolution after seeing how it works in a visual form.
All the best!
Andrew Darlow
If you’d like many more folks to know about this article, please DIGG it here.
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Tip: Changing Case Quickly In Microsoft Word
This is probably common knowledge for many, but I did not know about this until I recently stumbled upon this feature. If you highlight the text you want to change in a Word document and choose Format>Change Case, you can change the case of type in a few different ways.
For example, you can convert a paragraph of all caps (not that anyone would actually commit such a type offense, especially in an e-mail) to normal sentence case without re-keying the info. There are a number of other options as well (see below), such as Change to: Sentence case, lowercase, UPPERCASE, Title Case or tOGGLE cASE:
Let me know if this was helpful, and if you’d like more quick tips like these, just let me know which topics you are interested in by sending a note to imaging@andrewdarlow.com.
All the best,
Andrew
2
Review: my VoIP switch and experience with ViaTalk
Hello:
I thought I should post this review now because I’ve been very happy with the VoIP (Voice over Internet Protocol) service that I’ve been getting from a New York State-based company named ViaTalk. I noticed a few days ago that they have a significant discount for their VT_unlimited service. It works out to about $8/month($199) for two years of unlimited phone calls to the US and Canada.
OVERVIEW
The company also has an excellent referral program, and the links to the offer I mention will use my referral link. The pricing will be the same whether or not you use the link, but if you’d prefer not to use the link, just visit the company directly at viatalk.com.
For the last year, I have been paying about $55 each month for unlimited calling from my home and studio based in New Jersey. When I called Canada for 3 minutes a few months ago, my charges were over $10! Now I can call the US and Canada for under $15/month. I paid $175 for a year using a recent promotional offer, and I’ve had the service for about a month.
I have Optimum Online as my Broadband cable provider, and their service and bandwidth is excellent where I live, so that may have something to do with the quality.
Before the number was ported, I was given a phone number so that I could call out and receive calls as soon as the VoIP phone adapter arrived.
POSITIVE FEATURES
Apart from the pricing, here is what I really like about ViaTalk:
-Quality: I always get a dial tone and I rarely detect any difference in quality from my standard phone line. Occasionally, I will hear a word drop out, but I detect no other real difference, which is very important to me because I do a lot of consulting via phone.
-Customer Service: I have called the company three times and never waited for more than 5 minutes for a well-spoken customer service rep. The system actually tells you what number you are in line, and it counts down until you are caller number one. I have also used the live “chat” online and my questions were answered quickly. They have a “priority” customer service option, but I don’t see any real reason to pay for it.
-Number Porting: After signing up, I filled out a short form to have my home number ported, faxed it to them and received an e-mail that it would take up to 20 days to be ported. About 10 business days later, it was ported over (I knew because my traditional service just stopped) and I then called to have the number set for ViaTalk’s system. I then powered on and off the router, and I was done.
(Make sure you then cancel your other phone service to avoid future charges and get a name and phone number/id from the customer service agent in case you keep getting billed.)
-My VoIP telephone adapter has a phone jack port (actually 2, but only one is activated), and I am using a 3-handset cordless phone system, which is working very well. From the time I signed up online, I had the telephone adapter in about 2 business days. I decided to purchase it, but the current 2 year special being advertised now (two years of unlimited calling to the US and Canada for $199) allows you to receive the equipment for free. However, you need to keep the box and materials in case you want to return it in the future.
-Features: There are many features, which you can read on the company’s site, and the most important one to my family is caller ID. The caller ID works just like my caller ID did before, and when I asked the customer service rep how to make my built-in answering machine take calls instead of their answering service, she told me I could log in to my account and set the rings to a high number, such as 99. She then set it to 99 for me.
NEGATIVES/ADDITIONAL SUGGESTIONS
The main negatives to having this system are that I can not easily use the existing jacks in my house without going through a somewhat involved procedure. That means that my wife’s beloved 1970’s era rotary phones may be on their way to EBay or a dumpster soon. Also, if power, or broadband service goes down, so does the phone service. I recommend keeping a cell phone charged and nearby as a backup at all times.
I also recommend programming your local fire and police station numbers into your home and cell phones, even if the 911 service works fine, which it seems to be. You can ask the company about how the 911 service works.
CONCLUSION
That’s all for now. I believe that ViaTalk, as well as the fax service I reviewed in the right-hand sidebar from Trustfax, are both excellent ways to save money on important home and business communication tools.
Two of my relatives have VoIP service from another VoIP provider, and they pay about $25/month. They will both probably be switching this week to ViaTalk.
To find out more about ViaTalk, visit them here. Feel free to send me an e-mail at imaging@andrewdarlow.com to let me know what you think of ViaTalk’s quality if you decide to start using their service.
UPDATE: 9/6/2006: After I posted about not being able to use our existing lines and my wife’s treasured rotary phones, I checked the web and found step-by-step instructions to do it. https://michigantelephone.mi.org/distribute.html Now even our rotaries work (well, we can’t dial out). Plus, we removed the ringers just to be safe. Now I also don’t notice as many dropouts so I’m a happy camper.  -AD