Hello and apologies for what I am sure is an extremely tedious question. I have struggled to understand the relationship and best practice between size and resolution etc for like my whole life, it just wont click. I thought I would use some working examples and maybe someone could help me understand?
So like, I made a vector illustration in Illustrator at 72 dpi (dpi doesn’t matter for vector images does it?). I made it 1000 x 1000 pixels cos that is the size that was requested of me by the team/I guess the size it was going to be displayed at. When I exported it though, it was a bit jagged and blurry in places when viewed at full size. So I tried exporting it using 2x scale. When I did, the image was obviously bigger, but also when I resized it on the screen to be the same size as the original, it was still much clearer. This is because there’s literally more pixels, so more visual information, right? My question is then I guess, should I always be working at/exporting at double the size of the final image, and then just resizing it down?
-My second question is this: I made the components for an email signature that our IT dept is then using HTML to put together. Basically, it’s just some logos down the bottom and they needed them to be, say, 500 pixels wide. So, I resized the vectors to 500 pixels wide then exported them as PNGs at 72 dpi using the 'export for screen' option. But when they used them, they looked super blurry, like really bad. Would the better thing to do be to scale them to two times the size like the aforementioned image and have IT reduce the size again in HTML?
I think one of my biggest confusion points is when I should be worried about DPI and when I should be worried about pixels. I thought that whenever something is going on the web, it should be 72 DPI because DPI is only relevant for printing. BUT – when I exported the signature logos at 300 DPI to see what would happen, the images were crisper, and bigger – but they kept their crispness when I resized the preview window to be smaller on my desktop.
TL;DR: What DPI should I be using for Illustrator documents? If something is coming out blurry as a PNG, should I continue to just scale it at 3x or 2x when I export? If screens use 72 dpi, why did it improve the clarity of my PNG to export it at 300dpi?
Again, so sorry for such tedious questions, I am just hoping that using real examples someone will be able to explain it to me.
First of all, in this case it needs to be called ppi, not dpi.
When exporting for the web, the ppi really just doesn't matter. What matters is pixel dimensions. The device or the application then displays this at whatever size the coders instruct it to.
When putting several logos into a 500 px email footer, expect them to be blurry. There just aren't enough pixels in it to render those logos. Making the graphic bigger (1000px) and then scaling down is a method to deal with it, but unfortunately also makes the graphic heavier (more KB). Your choice. I would prefer not to have this kind of graphic in emails at all. Just text.
In Illustrator the 72 ppi is somewhat hardwired into the export of raster formats. Export at 72 ppi in order to get a raster image with the same pixel dimensions as your artboard.
The ppi you set during file creation is just the raster effects resolution and is not related to the exported image resolution. A vector file doesn't have a resolution.
In addition to what Monika said, to at least match any possible tediousness of your post, the following may sound unforgivably outdated and boring, sorry.
If you wish to have PNGs (PNG24 (also (little) known as PNG32, it holds 24 bit colour and 8 bit Alpha channel (transparency)), of course) look crisp and clean, at least when it is (also) to be used at moderate screen resolutions, it is important to have the images in the exact desired final pixel x pixel size, or at sizes that are powers of 2 times as large (2x, 4x, 8x, and so on, the larger values can improve the appearance on high resolution screens and still ensure best possible appearance at low resolution screens); forget about resolution which may actually lead to wrong sizes and hence blurriness, or work at 72PPI or powers of 2 times as large (144PPI, 266PPI, 576PPI, and so on).
It is easiest and safest to work at the desired size when creating the artwork.
It is important to remember that a raster image represents the whole appearance, including strokes, so to make sure you get it right you can click Show Preview Bounds in the General Preferences (and untick it afterwards).
A very common unsuitable way is to Export to PNG (remember to use PNG24 and use Transparency for artwork to be in front of different backgrounds) with a medium or high resolution, such as 300PPI.
And a common misunderstanding: (almost) 11 out of 10 times, a statement like "I created the document at 300 PPI" means that the value is chosen in Effect>Document Raster Effects Settings; however that only means that the (current) resolution of any raster effects applied to the vector artwork, such as (any kind of) Blur, is set to that value (and only unless/until the value is changed to something else); when zooming in, this resolution can be seen in contrast to and on the background of the vector artwork. So this setting has nothing whatsoever to do with the actual resolution of a raster image created from the (vector) artwork (but it ought to (at least) match it).
For clean and crisp artwork avoid JPEG.
It is also important to have the artwork and also the Artboard placed fully within integer/whole pixel X and Y values in the Workspace, which means that the X and Y values at the corners must be integer; this can be ensured by using one of the corner Reference Points in the Transform palette, and then checking that all the values X, Y, W, and H, are integer (the centre Reference Point can only be used if both W and H are even numbers).
Otherwise the resulting image will become a bit wider/taller and the extension(s) will be empty and therefore be (partially) transparent/white.
Therefore, the safest way is to create the artwork at the final pixel x pixel size and use a corresponding Artboard, then use the Legacity Save for Web (where you can look in the Image Size window for size confirmation and possibly multiply by 2, 4, 8, whatever), or use Export at 72PPI (or 144/288/576/whatever PPI), or use Export for Screens (in either way). In either case, use the relevant optimization (available with both ways); it is also convenient to have 72PPI (or 144/288/576/whatever PPI) in the Effect>Document Raster Effect Settings.
If you have pure vector artwork, you can relax a bit and have the artwork/Artboard at any size (the Artboard must have the same proportions as the final image), then use the Legacity Save for Web and set either Width or Height in the Image Size and Apply (make sure the other value is also correct).
The Legacy Save for Web may be an old carthorse, but it knows its way home, even if the driver is drunk and sleeping it off in the hay in the back.
Or you can switch to SVG, if applicable.
Oh, this was excellent! I am literally going to print this out and put it up behind my desk!!! Thank you for taking the time to write out such a detailed answer! What I still dont get though, but probably should understand, is why is it that when I make something at 1000 x 1000 pixels in Illustrator and then export it at its original size as a PNG, would it look blurry at all? Like shouldnt exporting it at the scale it was created at result in the most faithful PNG representations?
I was reading about someone who makes small web ads and they said" "For the most part I build the ads in Illustrator, export for screens at 4x the actual size, and then use Photoshop to optimize/reduce the ads to actual size."
So it seems like the workflow is create work in illustrator, export at 4x size, then reduce it back down to 1x in photoshop. Why do they need to do that photoshop step? Why doesn't exporting at 1x in the first place result in the same quality?
Again, apologies for needing things so spelled out - I am sure most people could infer this from the info you gave, I am just pixelly-challenged 😞
Similarly I just saw this:
ohhhh I just reread your reply!
"the larger values can improve the appearance on high resolution screens" so its possible that the reason it looks not as good at 1x on my screen is cos I have a higher-resolution screen?? (Its a fairly recent imac)
For my part you are welcome, Ead.
And you are right. And crucially, the only way to know how things look on screens with lower/different resolutions is to see it on one or a few.
Thank you so much Jacob!
You are welcome, Ead.
Please don't put the same questions into multiple threads. This will only keep multiple people busy without knowing of each other.
Sorry Monika, I thought they were different enough but you are right - will keep to same thread next time!
Just ask for dimensions in pixels. Usually, for the web they use sets of icons/illustrations. Resolution, as the others wrote, for web illustration is quite useless as every display has different screen resolutions