GoofyNewfie Loc: Kansas City

:thumbup: :thumbup: :thumbup:

BobbyT Loc: Southern California

QUOTE: DPI=dots per inch: NOT PPI ( PIXELS PER INCH). Thats the whole point here!

TheDman Loc: USA

Because it doesn't exist.



Because none of you knew any better.



It's just like the one from Adobe - incorrect. But why discuss this ad nauseum when this is all very testable and provable? Here is the same image, saved at three different ppi settings.

1ppi - http://www.ddphotos.com/vik_1.jpg
72 ppi - http://www.ddphotos.com/vik_72.jpg
9999ppi - http://www.ddphotos.com/vik_9999.jpg

Feel free to save them to your computer and verify the ppi settings yourself. According to you, those images should look radically different on the screen and have extremely different file sizes. However, they all look exactly the same and are the exact same 116kb file size! How is this possible, if what you say is true?

This is the part where you back out of the discussion, because as we've seen over and over again, I can prove my point and you cannot.

TheDman Loc: USA

You said "With the advent of super high resolution monitors, 72 dpi is not sufficient". What does DPI have to do with monitors?

burkphoto Loc: High Point, NC

The three files are identical except for the resolution setting in the header. Internet browsers IGNORE resolution settings. They simply display actual file dimensions in pixels, at the current monitor resolution.

SOME web sites automatically downsize over-sized uploaded images for display within the confines of their page designs.

If you were to import these files into a page layout application, or into pro photo lab printing software, you would see three different sizes of the same image.

BobbyT Loc: Southern California

DPI is the resolution of the monitor. PPI is the resolution of the image.

TheDman Loc: USA

Exactly, because those applications are showing you a print preview. Also, if you opened each image in Photoshop and tried to type text on them your text would be wildly different, because point size is tied to the physical world, which is what ppi translates your image to.

TheDman Loc: USA

No. Your monitor is simply a grid of pixels. DPI is a measure of how many droplets of ink a printer sprays onto paper.

scsdesphotography Loc: Southeastern Michigan

Thanks burkphoto, Your first reason for going to a lower res to prevent unauthorized use is good and I do remember having to change a profile pic one time. The original image I posted just displayed my right eye, had to change that, otherwise most places seem to have a maximum file or res requirement. For some places a tiff file is too large, so I upload jpeg instead.

burkphoto Loc: High Point, NC

:thumbup:

burkphoto Loc: High Point, NC

The standard for web page display of images is 8-bit JPEG files in the sRGB color space.

Although web apps IGNORE the file header resolution setting, you should normally base your Internet web page image display size calculations on 72 dpi, which is the worst case scenario for displaying images on a monitor. The default monitor size is 1024x768, although there are many larger monitors these days. 1280x960, 1920x1080, and 3840x2160 are becoming common. An 800x600 pixel image will fit nicely on a 1024x768 monitor screen, with space to spare.

There are exceptions for some sites which can make use of high-res files (files with large pixel dimensions to be displayed on retina displays)...

burkphoto Loc: High Point, NC

A lot of the confusion comes from the electronics industry, which has relentlessly used PPI and dpi interchangeably when discussing monitors and scanners.

Ignore 'em if they can't understand the difference. Pixels exist in files. Dots exist on paper and other display devices.

It is helpful to understand that a dot and a pixel are the same on a monitor *only* when displaying an image at 100%. Otherwise, pixels are in files, dots are on output devices and prints. I know we still *call* them pixels, for certain arcane technical reasons, but for the sake of clarity... (sigh).

Scanner vendors call pixels dots, in their software, as a holdover from the graphic arts industry's early days. Once upon a time, they WERE dots. The dots were created via analog methods and devices.

Now, scanners save those "dots" as real pixels in the same digital formats as digital cameras. But the manufacturers still call the damned things dots! Out, damned spot!

("Arf!" went Spot, pawing the door...)

amfoto1 Loc: San Jose, Calif. USA

Actually, one printer I work with recommends 170 ppi minimum, for very good print quality. That would make a 23x35" print from a D7200's 24MB 6000x4000 pixel image.

I try to use 300 ppi most of the time, too. But it really depends upon the output. Most photo quality inkjets and printing processes actually don't need more than 240 ppi. A few use as much as 400 ppi, though (Fuji Crystal Archive?).

All this is strictly image resolution. It's not "dpi" or "dots per inch", which is a commercial printing term related to halftone prints. A halftone is the conversion of a contnuous tone image into tiny dots, fewer of which allows more of the white of the paper to show through, or at their densest will render black. 140 to 170 dpi is what's used high quality magazines and books. Newspapers use between 90 and 120 dpi typically. These relate to a single plate, too... such as a black and white print would use. A color image normally uses four plates, each a separate halftone, that combine to make up the image. So a full color image would be done by passing the page through four separate printings (Cyan, Magenta, Yellow and Key/Black or "CMYK" ), so in effect there actually are between 360 dpi and 680 dpi to make up a full color image.

It's also not the same as inkjet resolution, which is often 1440 ppi or greater. Here, once again, a series of dots are applied to the page and a single pixel from the original image file might be rendered by 6 or more of those dots (depending upon the inkjet printers resolution).

I've experimented with various image resolutions printed on inkjets and there's very little gained beyond 240 ppi. I've gone as high as 720 ppi and really didn't see any better results beyond 300 ppi. So that's what I use. Plus the math is usually easier than 240 ppi... At 300 ppi a 4x6 print is 1200x1800... a 5x7 is 1500x2100... etc. Easy!

I've also "uprezzed" images with very good success. Most will easily hold up to 200% increase, some as much as 300%... especially if it's done in steps. That's without using any sort of up-rezzing softwares, some of which seem pretty good and might make even more possible.

imagemeister Loc: mid east Florida

Here is what I will say -

Fine Art America guarantees the satisfaction of their printmaking. THEIR file requirement is approx. 135ppi for ALL print sizes. I size my files to 165PPI and get beautiful 18X24 in.prints - even have a 36in wide print also and (fussy me) am completely satisfied.

imagemeister Loc: mid east Florida

:thumbup: - the sharper the image and the more pixels to work with the better the outcome ...