TheDman Loc: USA

Printing PIXELS, not inches. This is why the pixel dimensions determine how large or small the image appears on your screen, but not the dpi.




The origin of the 72 ppi screen resolution dates all the way back to the mid 1980′s when Apple released its first Macintosh computers. These computers included a built-in 9 inch display with a screen resolution of 72 pixels per inch. Why 72 pixels per inch? It’s because the Macintosh screens were specifically designed to work in perfect harmony with Apple’s ImageWriter printers, which had a print resolution of 144 dots per inch – exactly twice the resolution of the screen. This made it easy to scale the screen display to the printed page, which meant that your text and graphics could be previewed on the screen at the exact size they would appear when printed. Later on, as Apple began making larger displays for the Macintosh, they made sure to keep the screen resolutions set to the same 72 pixels per inch so users would always see an accurate on-screen preview of the printed document (as long as they were using an ImageWriter printer).

But the 72 pixels per inch screen resolution was a standard only with Apple, and it didn’t last. Third party companies selling monitors for the Macintosh didn’t stick to the standard, and neither did competing PC monitors. Today, nearly three decades later, technology has greatly improved and the days of screens with a resolution of only 72 ppi are long gone. Even Apple, the company that started the whole thing, now sells their displays with much higher resolutions. No one is making 72 ppi screens anymore. No one is using 72 ppi screens anymore.

TheDman Loc: USA

In fact, a digital image, on its own, has no inherent resolution at all. It’s just pixels. It has a certain number of pixels from left to right and a certain number from top to bottom. The width and height of an image, in pixels, is known as its pixel dimensions, and that’s all a computer screen cares about.

The size at which an image appears on your screen depends only on two things – the pixel dimensions of the image and the display resolution of your screen. As long as you’ve set your screen to its native display resolution as we discussed earlier, then an image will be displayed pixel-for-pixel. In other words, each pixel in the image will take up exactly one pixel on your screen. For example, a 640×480 pixel image would fill a 640×480 pixel area of your screen. An 800 pixel-wide banner on a website would appear 800 pixels wide on the screen. No more, no less. And no matter what you set the image’s resolution to in Photoshop, whether it’s 72 ppi, 300 ppi or 3000 ppi, it will have no effect at all on how large or small the image appears on the screen.

That’s because image resolution affects only one thing – the size of the image when it’s printed. By setting the resolution in Photoshop, we tell the printer, not the screen, how many of the pixels in the image to squeeze into an inch of paper. The more pixels you’re squeezing into every inch of paper, the smaller the image will appear when printed. And generally speaking, the more pixels you’re printing per inch, the higher the print quality.

Kuzano

Do it all at once ... Bite the Compression Bullet ONE TIME.

Set save quality (compression) at the max (least compression)

Doing incremental saves on a compression algorythm will run the algorythm each time saved, if using compressible TIFF or in particular Jpeg.

If you do it in increments, use file editing formats that do not compress until the final one. Ie, In photoshop used PSD, or non compressed TIFF.

I still would never do incremental reductions. Just one time.

Last two work flow items... sharpen, then reduce. Perhaps the other way around.

imagemeister Loc: mid east Florida

FYI - I have been to your link - and many others. If you "CONSTRAIN PROPORTIONS" and "RESAMPLE IMAGE" in Elements - when you change the PPI, it changes the overall pixel numbers. So, you can use 96ppi just as a gage for reduction of your pixel count to give the approximate monitor image size you are looking for. As such, it is just a computational element - again with no DIRECT correlation to how many PPI the monitor is actually showing or providing.

TheDman Loc: USA

Why would you do that though? When you set out to email a photo or post it to a website you must have a desired pixel dimension in mind, so why would you not just change the image to that exact number of pixels, rather than use the tail to wag the dog so to speak and change the ppi, hoping you get close?

The 'resample image' feature that allows you to change pixel dimensions when you change ppi is for print sizing. If you want to print an 8"x10" photo at 300 ppi you can simply input those numbers and Photoshop will resize the image to match.

sjbegres Loc: Pittsburgh, PA

Is FastStone Image Viewer better than Photoshop Elements 11 for resizing, which is what I have been using?

amehta Loc: Boston

I have never used photoshop or photoshop elements, so I cannot say which is better.

countrydan1

Thanks for the precise and important information . You folks really impress me with your knowledge of photoshop. I shall try both methods, since they are much better than the method I was using. It is a crime to take what could be a good shot and mess it up in post-processing. Thanks again. Dan

jamesl Loc: Pennsylvania

I created the two attached from your original and resized them. I resized the original TIF first, then converted it to a JPG and set the quality.

25% Size 90% Quality

(Download)

50% Size 90% Quality

(Download)

Original TIF

(Download)

dar_clicks Loc: Utah

You've noticed something important -- re-sizing changes the appearance of a photo, particularly sharpening and sometimes even color.

The purpose of the re-sizing can make a difference, so I'm only going to speak from experience of resizing downward to get a better e-Mail size. I've used a resizing plug-in in both Elements and Photoshop. Usually the plug-in does a better job but sometimes the downsized photo looks better using one of the Photoshop options (kinda depends on the subject!). Sometimes a very slight noise reduction has to be done first (not enough to destroy sharpness) in order to keep from having artifacts introduced.

Sometimes experimenting a few times with various sliders or settings can lead to a result that looks best and you can find what looks best to you most of the time from then on.

tuffsheet Loc: WPB FL.

Lots of great information here....Thanks for those of you who participated!

Nan333 Loc: near Baltimore, MD

For all my images that I may want to print, I crop if necessary, then in Image Size unclick Resample Image. Then change to 300 Resolution. Then change the size in inches. Then make Adjustments (Enhance). I learned this from Photoshop Elements 5 book by Scott Kelby even though I have Elements 9. It is my bible. He writes well and with humor.

Alby144 Loc: Northern Nevada

Who would have known re-sizing an image would be so controversial? I've been re-sizing for years and have seen no image degradation, but my purpose may not be as critical as some of yours. I e-mail them, post them to forums, print them and use them for wallpapers on my PC...