AI giving different dimensions when saving PSD files

[Regina 7]

Would like to understand what is happening here.  I have a PSD file and I flatten it to 4 layers then save the file (but leaving it open in PS)  > I go into Bridge , choose that same saved PSD file and open with AI > Save as AI file.  The resulting AI file size can be wildly different even thought the settings are the same and the file is saved the exact same way.  

Example:

PSD File is 2850 x 2850 @300 ppi

first time I saved this as an AI file is saved as 648 x648 @300 ppi 

When I did it again, same file, same settings, same everything, it saved as the same size as the PSD: 2850 x 2850 @300 ppi

waht is going on here? thanks.

[Monika Gause]

I don't understand the workflow.

Why are you opening that file with Illustrator?

Sizes of files are a completely different thing in Illustrator than in Photoshop. You can't compare that.

[Regina 7]

Because  it creates a smaller file. In this case the PSD is 10 MB and the same file saved as an AI file is 6MB. This is small in comparison to others I usually send, but I am sticking with the same example here. Aslo, the factory I am working with often requests AI vs PSD files and the intricately detailed waterecolor artwork (in this case) cannot be converted to vector files.  If you know a better way I am all ears.

I am not trying to compare file sizes in PSD and AI, I am trying to understand why the same file would save at two wildly different dimensions (648 sq vs 2850 sq) when I save it exactly the same way. 

[Monika Gause]

Export it as a TIF file without layers.

[Regina 7]

I need to retain a few layers and a reduced layer TIFF; when both have the same number of layers the AI file is still smaller than the TIFF

[Ton Frederiks]

Illustrator just scales the image to honor the 300 ppi set in Photoshop.

The amount of pixels is the same, the image is scaled 24 %.

[Regina 7]

I kind of get what you are saying, but why would the file save it as 648 sq vs the next time I save it the same way it saves it as 2850 Sq?  I have attached a screen shot of what I am talking about. this is a differnet file than the one I have been referring to, but it is the same question.  Just wondering why it would save seemingly indescriminantly at two different sizes.  

[Ton Frederiks]

If you use a resolution of 72 ppi you will get the size in pixels that is the same as the pixelsize in Photoshop.

Because you tell Illustrator that the amount of pixels have to be condensed to 300 pixels per inch it will show you a smaller image on the artboard. Pixels per inch is just metadata, it does not change the real amount of pixels in the file. A pixel does not have a fixed size. Illustrator has to assign a default size for a pixel, so it uses 1/72 of an inch for a pixel as default. The higher the ppi the smaller it will be displayed in Illustrator (and the other way around).

[Regina 7]

I'm not sure my photo was viewable before.  Not sure I completely understand.  If my PSD files are 300ppi and I am opening them in AI, then saving as an AI file, is AI randomly deciding which resolution to view it at? in each case I am not assigning any resolution or changing any settings.  they are identical in every respect except for how AI decided to save them. I didn't change any resolution. 

[Ton Frederiks]

Illustrator can show the print size at 100 % zoom if you set it in Preferences. It will calculate the print size using the amount of pixels and the associated ppi.

[Regina 7]

Not sure that explains why when when the exact same file is saved twice the same way maybe 3 minutes apart it saves it with two different sizes; preferences are unchanged between each action. 

[Ton Frederiks]

I cannot replicate that.

[Regina 7]

Ok, thank you for your help anyway. I appreciate it.

[Ton Frederiks]

Thanks, I hope you understand now the relation between print dimensions and resolution. It is complicated because for Photoshop the size of a pixel does not matter, at 100% every pixel has the size of one pixel on screen, but for design apps, the resolution decides the displayed and printed size.

[Regina 7]

yes, I understand the relationship between print dimensions and resolution.  I just don't understand what is happening here: saving the same 300ppi PSD document out of AI and having it save with two different dimensions as reflected in the metadata. otherwise on screen both docs look the same and have the same info, scale the same, etc  Just for kicks, I am showing the two with info on screen.  Each screenshot has a small image of its respective differing metadata. The factory doesn't seem to have an issue producing decals from the files either way or I'd have heard about it ages ago.  This is for my own understanding about what is happening.  Again, thanks for your time on this. 

[Ton Frederiks]

What do you use to get that little metadata panel?

[Regina 7]

Adobe Bridge

[Ton Frederiks]

Thanks, I wonder what the difference in saving the files is to get the different view of the metadata. Both are right, depending how you look at it.

[Regina 7]

Yeah, that was the ultimate question.  ¯\_(ツ)_/¯ 

[Ton Frederiks]

Yes, but you are the only one who knows the exact steps to get to these differences. I don't know how to get that result...

[Regina 7]

Open PSD file > flatten layers so all art is in one art layer, background later, layer containing text info > Save > go into Bridge > right click that saved PSD file > Open with Illustrator > Save As > close AI file ( i return to the PSD file and return it back to its original multi layered state, but this is inconsequential to the final AI file).

That is how I do it every time. Results vary.  When it is saved as the smaller 648 sq and I happen to catch it, I will do the same process all over again exactly the same way and usually I get the larger dimension result.  No idea why.

[Ton Frederiks]

Thanks Regina, I'll check it out tomorrow.

[Ton Frederiks]

I am afraid that Bridge is giving wrong information. An Illustrator file with an 3300px image at 300 ppi is shown with dimensions of 6,7 x 6,7 cm in the metadata. In the Illustrator Transform panel it shows as 27,94 cm, same as Photoshop does.

[Regina 7]

Interesting.  I looked at both of the examples above with more metadata selected to display and this is what I got:

for the one displayig  792 px Sq @ 300ppi  the metadata is showing 6.7 cm sq, but the transform panel shows 19.3 cm sq.

For the one displaying 3300 px sq @300ppi the meadata is showing 27.9 cm Sq. but the transform panel shows 19.3 cm Sq.

so you are right, it seems to be a Bridge thing. Do you think it is giving me the thumbnail size? There is a difference in scale when I hit the spacebar to preview the images in Bridge.  the 792 gives me a smaller preview than the 3300 does. thanks for sticking with me on this.

[Ton Frederiks · Accepted solution]

Luckily this does not affect export or print. You may want to check the Bridge forum, maybe someone there can explain it: https://community.adobe.com/t5/bridge/ct-p/ct-bridge?page=1&sort=latest_replies&lang=all&tabid=all