1 Correct answer
Video in general doesn't know DPI. Video is always rasterized and the size of a pixel depends on the hardware only.
On large screens (public viewing), usual the pixels are very large, too. A higher DPI doesn't make any sense for this, even if it would be possible to set it up. *Martin
12
Replies
I will try and make this simple. High-resolution images have a lot of pixels. The more pixels, the more data, the more data, the higher the resolution. Unfortunately, even people that teach in universities don't make this clear and use the wrong terms. Video, the web, mobile devices, all electronic devices that are capable of displaying images use pixels. You want high resolution, you supply more pixels. Here's a fun test that you can run. Download both of these images. They are exactly the same resolution - the same size. Drop them both in an app designed to print images like Word or In Design. One of them will be hard to see, the other will more than fill a page. The PPI metadata in an image file just tells the printer or the page layout program, how many pixels to print on an inch of paper.
I hope this helps you figure things out. There is no video standard that includes pixels per inch.
There is no tag, 72 is the default assigned to any image without a PPI tag in the metadata. GIFs don't even have a place to store PPI in their metadata so you can't assign a print resolution to a GIF.
You could easily run a batch in Lightroom, Bridge, or Photoshop to change the tag to 96 without resampling the image. What do the two jpg's I uploaded look like in Outlook? When I open my version of Outlook and attach those two images to an e-mail there is no difference in the size and one is 1 PPI and the other is 9999 PPI...
Admittedly that's Outlook for a Mac, but the images are exactly the same resolution (number of pixels) even though there is a huge difference in the PPI tag. Try an image yourself in your version of Outlook. Make one of them 1 PPI in Photoshop, the other 72PPI, and make one 9999PPI but don't resample so they are the same pixel dimensions. I would be very curious to see if there is any difference. Even though I don't recommend it I've uploaded the two images in the post so they will be easy to download and test.
There is no such thing as DPI in an image. DPI refers to the number of dots an image scanner can capture per inch. There is no DPI setting in Photoshop or Illustrator. Some developers use the terms interchangeably but that just leads to the confusion that DPI is a measure of resolution. It is not. Resolution is the number of pixels.
I'm not the only one who was dealing with this Outlook issue (see links). But in the latest version, it seems to be back to normal 🙂 So thanks for challenging me to investigate it again!
https://www.extendoffice.com/documents/outlook/3851-outlook-insert-picture-with-actual-size.html
https://blog.gimm.io/how-to-fix-blurry-pixelated-or-fuzzy-email-signature-images/
Some extra arguments and remarks to support my feature request, though:
1. "There is no DPI setting in Photoshop or Illustrator"
In Illustrator obviously not - that's a vector drawing app!
In Photoshop - yes, there is. Please open the Image Size dialog to see it.
And sure, the dpi are related to actual paper sizes, which is logical. When choosing not to Resample, the pixel count stays the same - resulting in a different size when printed - of course.
For print, it is convenient - apart from having a lot of pixels, to set the ppi to >254, because the size when imported in e.g. InDesign depends on that. In that way the size at import is the 'original' that has enough spatial resolution to be printed nice and sharp. See how the same image imports in InDesign, with 3 different ppi settings.
Again: it's nice when an image imports at the intended size. When it's way too big, because of the standard 72ppi, the designer could easily think that it's a high resolution image, which it isn't.
(note: In print, a 300ppi image has to be halftoned in a much higher resolution. The halftone dots [which are spaced in lpi - lines per inch] are build in a spatial resolution more than 2400 dots per inch, for professional offset print.)
2. If it's not needed, and there is no tag (or metadata), why can Lightroom, Bridge and Photoshop change it in a batch process? And why not enhance Ae to be able to do so? What is the downside?
3. "Resolution is the number of pixels'
That's an arguable statement. When comparing two devices or files, it is true. Number of pixels is a relative resolution.
But it's of less use when it comes to the commonly used terms 'high resolution' and ' low resolution'.
In absolute terms, when no output size or medium is given, the number of pixels is not enough to know whether the resolution is high or low. 1920 x 1080 px is high definitition, and for an sd screen, it is high resolution. But not on a 4K display, or printed on a bill board. A photo containing 1200 x1800 px can be rather hi or lo resolution, depending on the size it's gonna be printed. For a passport photo, it may be enough, but for a movie poster it's far too less.
I thinks it's good to distinguish image resolution and spatial resolution, the latter is used for detail in relation to size.
4. I was not talking about .gif, most modern image formats do have a ppi in their metadata.
But to be short: why not add a ppi setting to Ae image output modules? Makes some workflows much more comfortable, without having to go to another step in another app. Ppi is an image parameter anyway. I think it's not hard to add it. (and Ae may continue to ignore it at input)
AdChoices
