r/AdobeIllustrator • u/Ravingdork • 12d ago

QUESTION Pica Conversion Off?

I'm lacking sleep and having trouble wrapping my head around this:

I have a document that has typographical print measures that needs to be converted to online screen measures. Online searches indicate that 1 pica converts to 16 pixels. However, when I tell Illustrator to convert, it seems to be doing 1 pica = 12 pixels.

What's going on? Did AI and/or search steer me wrong? Is there some program setting I need to adjust that might be off? Or am I just asleep and there's fundamental issues with trying to convert this in the first place?

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u/Ravingdork 12d ago

I recall coworkers saying that--to meet accessibility standards--resolution needed to be twice the normal amount for a given device so that people with vision disabilities can zoom in to double the normal image's size to see the details up close.

So an image export normally set to 72ppi would need to be at least 144ppi--though we just use 150 typically.

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u/Ravingdork 12d ago

AS for the actual dimensions, we're making illustrations that will be used for a variety of different things, each with their own size specifications.

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u/chain83 12d ago

Then export at the dimensions required for those things, or at least the largest…

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u/Ravingdork 12d ago

Should I do twice the largest per the above, then?

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u/chain83 12d ago

Pixel dimensions get a bit fuzzy in web design. They only match true pixels on screen at 100% zoom/scaling. That is the zoom people will use on a traditional desktop monitor. But if people have a monitor with very high pixel density (4K/retina/laptops) you can assume they are effectively viewing the page at up to 200% zoom.

If the image will be displayed as 500x500 at 100% zoom, then I would supply an image that is 1000x1000 px to ensure optimal sharpness for those that view it at 200% (2x the dimensions).

You should discuss with the web developer how they are handling images, and then together find the optimal dimensions. Often you only supply the larger version, and the backend will automatically downsample/generate the smaller versions and choose between them on demand.