Where to find the transparancy of a color in an .eps file

[yannickb90881664]

I'm working on a project and i'm not really experienced with this. I want to make a plugin where users can upload only .eps files. But there's a catch...

The user can only upload .eps files and these files can not have transparant color in it. I thought of something to search for specific transparancy value and if they are there the plugin won't accept the file. But actually i don't know anything at al about .eps files. I hope somebody can teach me the basics or help me find the terms i have to look for in the file to not accept it.

I have made 2 .eps files one file contains a transparent color the other doesn't. I've noticed that the file which does not is much shorter. Also the file with transparency in the color has a fall back image and is much longer. Is this because of the transparency color or are there other things. I will ad the screenshot of the difference between the files.

[Ton Frederiks · Accepted solution]

EPS files cannot contain transparency. What you see is probably the Illustrator part of the file.

[yannickb90881664]

So is if there's a fallback image like on second file, it's not a correct .eps file to use for print work?

[Ton Frederiks]

The Illustrator part that is saved with some .eps files is meant to be used by Illustrator when the file is reopened.

This part is not the .eps part, which will lose many editing capabilities.

[m1b]

Hi @yannickb90881664, how are you generating the .eps files? If you are exporting .eps from Illustrator, it may be rasterizing section(s) of the page due to transparent elements which are not compatible with the .eps format (as @Ton Frederiks noted). That would explain why the file size is larger—because it contains the raster(s). I think it may be challenging to programmatically determine if the .eps code (ie. PostScript language code) has signs of being converted in this way unless you familiarize yourself with all the things that Illustrator does to "flatten" the file, and identify those things as tell-tales in the postscript. But what if one of your users gives you postscript generated with a different app, not Illustrator—it may have different tell-tales. Maybe someone has a quick fix, but I think it'll be a hard job you have set yourself.

- Mark

P.S. I wonder if .eps files are a bit old-fashioned to be working with these days? I haven't used one for 10 years at least.

[yannickb90881664]

Thanks a lot for the explanation.  I have generated these files in illustrator. The reason why i need it to be in .eps files is because the plug-in will be for a printing company. But this is pretty dissapointing, although i think most of users who will upload .eps file made it in illustrator. If we only inform people they have to use the illustrator style is there a way to search for specific words or variables that will be used to set transparancy in the .eps file. I think it will not work because it is to complex to me but if we can make it happen it would help the company a lot.

[m1b]

Perhaps you could require an .ai file instead? Then it would be easier to just open it up and check for transparent objects. It would still be a fair bit of work to write that script but I think it is much more feasible than using .eps files.

- Mark

[yannickb90881664]

So your workaround is they upload an .ai file. Then the plugin will open in Illustrator to check if there's transparancy in colors. If there's not it will automatically export to an .eps file. If there's transparancy in the colors the user will get an error from and needs to edit the colors. This is brilliant i hope i can find someone to help me with this. You guys are great, although i still have a question. I hope you can help me with it. 

Do you know if there's an easy way to check in an ai file if there's tranaparncy in the colors?

[m1b]

I'm not sure if there's an easy way. There might be. But a brute force approach would be to iterate over each page item and check opacity, transfer modes (multiply, darken, screen, etc) and other things. But some effects (eg. drop shadow, or gaussian blur) also involve transparency and those effects are directly accessible via script. Hmm, other things aren't accessible via script either, for example if an item has a second stroke which is semi-transparent the script won't be able to see that, because scripting API doesn't have access to those extra appearance properties. Or are you making the plugin with the SDK? If so, you may have greater access to these things. Another thought is that, when exporting the eps, you may be able to disable all the "flattening" and rasterization which means that the eps will be "compliant" but the artwork will most likely be wrecked. Maybe you could research the transparency flattening that Illustrator does and when/where you can control it. Sorry I'm just thinking out loud.

[Luke Jennings3]

.eps files should usually be avoided, there is almost no reason to use them and many reasons not to use them. PDF is a better option. What plug-in are you using? there may be an update. That said, transparency should not be an issue for a modern workflow, however, you can use an Acrobat preflight profile to check a pdf for transparency. Tools> Print Production> Preflight.

[yannickb90881664]

Is there a way to check if the .ai or .pdf has transparancy in the colors without acrobat preflight profile? We are trying to create a custom plugin for in wordpress with php and some libaries. I've made 2 exact same files while one has transperncy in the color and the other one doesn't. I can see the one with transparency has something like transparency true. Is this the same when you use more objects in the vector? Is this the way to detect transparency in the source file? Thanks a lot for all the help and thinking 🙂

[Monika Gause]

The plugin Select Menu can select "Transparent Art", but I have not tried yet what exactly it can find. If this is reallly all kind of transparency.

[yannickb90881664]

I have tried it but im not sure, i want to know if it's possible to see in the file text without opening in illustrator. So is it possible to detect transparency from a .ai file when you look into the source code of the file? 

[Monika Gause]

It's a proprietary file format, so probably not unless you reverse engineer it.

You might want to tag your post differently, since this is about programming now.

[yannickb90881664]

Okay, thanks anyway. I will make a new topic about this.