As a webmaster, I often have to field tech questions unrelated to my job in the office. Usually this is no big deal; I generally give the answer and then move on. But the other day, a question was posed to me that really threw me for a loop.
I was asked why, when increasing the Pixels/Inch (ppi) in photoshop, a photo became bigger.
If you stop and think about it for a minute, this is a really good question. DPI (dots per inch) is used quite often in print circles; it literally refers to how many individual dots are printed per inch. With a DPI, more dots are squeezed into each inch, and the picture is therefore sharper; with a low DPI, there is more space in between each dot, and the picture is therefore of a less quality.
So when you increase the PPI (which one might assume is the same as DPI, except with pixels), you should be increasing the quality of the picture by making the dimensions smaller, right?
Wrong. If you try this for yourself in Photoshop, you'll find that the photo increases in size when you increase the PPI, thereby decreasing the quality—which is exactly the opposite of what you might at first expect.
It takes a bit of extra thought to understand what the logic is behind this. The key to comprehending this paradox is that while printed materials can vary the spacing between dots, computer screens cannot vary the spacing between pixels. So if you vary the PPI, you are increasing or decreasing the number of pixels in your image, not increasing or decreasing the space between the dots as with DPI.
So what does this mean? In a nutshell, this means that when you increase the PPI of an image, what happens is Photoshop adds in additional pixels, horrendously ruining the quality of the photo while simultaneously making the pixel dimensions increase.
The moral of the story: DPI≠PPI! If you're a print person who is just getting into web stuff, don't make the mistake of thinking that just because DPI count and quality are proportional that must mean that PPI count and quality are also proportional—on the contrary, they are inversely proportional!
And the figuring of this out is how I avoided looking like a fool in front of my non-tech-savvy coworkers. I hope this blog entry will help you to also not look like a fool. (But if it doesn't, it sure as hell isn't my fault.)
30 September, 2008
24 September, 2008
As many of you probably already know, my day job is as the webmaster of strength.org, a nonprofit dedicated to ensuring that no child should ever have to grow up hungry. Well, one of our initiatives, the Great American Dine Out, is going on right now all across the country. Simply by going out to eat at one of the four thousand participating restaurants this week (through Sunday, 28 Sept), you can help end child hunger.
M Street Bar & Grill with three of my coworkers. It was great. If you're ever in DC, I heartily recommend that you stop by. I've even added it to my custom google map of great places to eat in DC (for vegetarians).
But I of course realize that most of you aren't in DC, and perhaps even fewer are vegetarians. So instead, I want to give you guys links so you can find out which restaurants in your area are participating in the Great American Dine Out. So click on the major metropolitan area you live in to see a list, or type in your zip code here to find participating restaurants near you. And eat out every day this week—remember, it's for the kids!
10 September, 2008
I did not take a picture. I will not take a picture. Yet I feel like I cannot go on without showing a picture. So here is a picture I found on the internet.
My lawn is small. Too small to bother with, really. But the grass was getting long, and weeds were taking over, and Rosina asked me to cut it. So I did.
The lawn mower is a simple machine, powered not by gas but by gears alone. Yet as I plow through the yard, the blades turn swiftly -- far more swift than I imagined possible.
I am oblivious to the world as I mow. A song rages through my head and thoughts on the Large Hadron Collider consume my attention. So it is with surprise when I notice a rabbit jumping away from my feet, mere centimeters from where I had just cut down the grass.
That rabbit could have died, I thought. It almost died by my hand. The thought was sobering. I immediately stopped mowing. The song in my mind stopped playing. The LHC took a back seat to the close call I had just made.
That's when I noticed the rabbit's mate.
She lay behind me, almost invisible in the grasses. I had hurt her. I had damaged her. Not with my blades, but by rolling over her with the wheel of my lawn-mower.
For a split moment, I thought of how lucky she was to have missed my blades. But then I realized it was worse than I'd imagined. One of her eyes was red. She was bleeding internally.
My heart stopped, just as the rabbit vainly tried to jump away, with the entire left side of her body fully paralyzed. She pushed herself in circles, again and again, as I watched helplessly. This is my fault, I told myself.
Through carelessness, I had caused such unnecessary pain and suffering. Through pointless singing and idle physics wonderings that I've no business to think of while handling such dangerous blades.
She was dying, but slowly. Ever so slowly. Blood started seeping from one ear, though the blood in her eye lay locked behind the cornea. I had to kill her now. I had to, to end the suffering.
Rosina directed me to the only instrument of death in the house: a small shovel. I took it.
Carefully, I carried the poor rabbit to the woods beside the house. There, in the shelter of trees, I apologized for the seventh time to the rabbit before me. And I raised the shovel, ready to strike. I wanted to do it one blow.
But I could not even attempt it.
I stood there, shovel in hand, yet could not strike. I could not bear to kill her.
Softly, I returned to Rosina, and asked if she could do it. I asked if she could deal the blow that the poor rabbit needed so dearly. But Rosina, true to form, insisted that she could not. It was up to me. It was up to me, or else the rabbit would die a horrible death of slow agony.
So I returned to the rabbit, knowing I would blog this immediately afterward. Knowing that if I so chose, I could bring my camera to take a picture. But I did not. I could not.
Instead, I cut off her head, then crushed her skull.