Image Mask

[mansourbakhtomid@gmail.com]

Hello, I have many pdf files created from tiff files of scanned technical drawings which tiffs treat as what so-called an "Image Mask" in them when we analyze them with acrobat Preflight tool, now I want to know what an Image Mask is? How can I make a tiff treat as an Image Mask when it is converted to pdf in a simple way or with a tiny add-on or .exe software?

Thanks and Regards,

Omid Mansourbakht

[ls_rbls]

I've read quite a few times here in the forums that Acrobat is not an image editing software. As such , image masks are no really supported in Acrobat.

From reading a bit more, I 'v e learn that when a document that was produced with another applicatiom, and it contains image masks when it is exported to a PDF file, what most people do is optimize the PDF to remove certain objects, and in other instances flatten the PDF and/or reduce the file.

See what Acrobat can handle as far as images is concerned here: https://helpx.adobe.com/acrobat/using/edit-images-or-objects-pdf.html

Additionally see these two other discussion: 

• https://community.adobe.com/t5/acrobat/the-pdf-document-contained-image-masks-that-were-not-downsamp...

•  https://answers.acrobatusers.com/Add-clipping-mask-cropping-q301402.aspx

To really work with masks you need a product like Adobe Photoshop , for example. 

But to answer your question  a mask is defined in this excellent Adobe Photoshop quick tutorial with practice examples: https://helpx.adobe.com/photoshop/how-to/layer-mask.html

More practical explanations here: https://helpx.adobe.com/photoshop/using/masking-layers.html

[mansourbakhtomid@gmail.com]

Hi ls_rbls,

Hello and thanks for the reply, but my purpose is tiffs which treat as the thing so-called "Image Mask" in pdf, not clipping mask.

[ls_rbls]

Well, with my current knowledge of Acrobat, I think that the confusion is on how we're interpreting the concept of layering masks, which is done with image manipulation programs and photo editors. 

In Acrobat the concept may appear to be similar in the sense of how PDF layers are used.  But as I mentioned earlier Acrobat is a PDF editor, not an image editor.

As a PDF editor,  image files in Acrobat  (regardless if they were clipped,  masked or not by other producing software) need to be converted to PDF.   Then the PDF editing would involve layering; which I believe it is referred to PDF layering (not image masking; key detail since the image file has to be converted to a PDF first).

I think that is what you're referring to.

Is that is what you were referring to  then look at  this other guidance:

https://helpx.adobe.com/acrobat/using/pdf-layers.html

[mansourbakhtomid@gmail.com]

Hi, my before-mentioned pdf files are generated via a program/library called "DynaPDF" (I have seen some similar ones generated from PDFium) and I would think the "Image Mask" behaviour of tiffs maybe or should have been established by it, on the other hand I have found the structure (strings) of "Image Mask" by studying the "PDF References" publication of "Adobe", in the meantime I have visited some websites (e.g. Hummus PDF — Things you can do with TIFF images, pdfhummus.com/post/45501648846/things-you-can-do-with-tiff-images) which with association of "Github" has given some codes of C++ about the mentioned matter, but it is very confusing for me and I don't know what I have to do and how I have to start the work. How can I make a tiff treat as an "Image Mask" when it is converted to pdf in a simple way or with a tiny add-on or .exe software? is it possible to do it with Java tools of Acrobat Pro and just a few lines of codes?

[ls_rbls]

Thanks Test_Screen.

Mansourbak:

What you're asking is not possible with Adobe Acrobat.

I am sure there's a way of manually altering the PDF file formats but what you're asking for , and now taking into consideration the references that you've posted, is out of the scope of what Adobe Acrobat Pro is capable of doing by itself and in a simple way.

HummusPDF is actually abandoning the project and encouraging the Github community and followers to take over this project.

DynaPDF... very appealing and interesting. Specially on the Linux support part. But this also doesn't address what you're asking. As a matter of fact, they also disclaim that even though it is platform independent users will have to compile their own to make it work with certain operating system (i.e iOS).

The best sources that I could find  in support to this topic are somewhat described  in two blogs. 

Search for "3 examples of unusual ways to use PDF Image Masks"  by Mark Stephens, and "Understanding the PDF File Format: Bugs, Gotchas and Tips"   by Leo Atherton.

I hope this helps.

[Test Screen Name]

Why do you WANT to do this particular thing? Please be detailed about your motivation. What is wrong with the conversions you have? What image representation have the TIFF files? If you are not an experienced programmer, poking in github for sources isn't so likely to be productive.

[mansourbakhtomid@gmail.com]

Thanks for your reply, my motivation is to know what the differences between two conversion are (normal conversion in comparison to unusual conversion) and then apply the latter if has some benefits; by the way I am seeking a way to do that. (I am not a programmer and do not have any skills in programming).

Thanks and Regards.

[Test Screen Name]

I have explained all the technical details available about the difference between images and image masks. I find it hard to imagine you can do anything useful with this information, but I don't have any more. Good luck with your task. It sounds like an academic project. If it is, I suggest you seek clarity from your tutor. If it is a work project I suggest you ask your boss what his or her actual business need is. If you hope to learn programming, I suggest a different path.

[Test Screen Name]

An image mask is a special kind of image

Normal images:

- ignore the last colour used

- every pixel is opaque (unless transparency is applied separately)

- every pixel has a colour

- has a colour space (such as greyscale or RGB)

- has 1,2,4,8 or 16 bit data for each pixel

An imagemask

- use only the last colour used

- each pixel has either a colour or is transparent

- pixels do not have a colour, they are visible or transparent (on or off)

- have no colour space

- have always 1-bit pixels

How does an image mask compare to a 1-bit greyscale image?

- the image mask takes any single colour; pixels are that colour or transparent

- the 1-bit greyscale image will produce either black or white, never transparent

Image masks are often used for bitmap fonts.