Author Topic: Importing images with transparency  (Read 4703 times)

Karela

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Importing images with transparency
« on: May 07, 2014, 05:19:32 pm »
I am trying to import a logo with a transparent background in a .tiff format, but it keeps importing a completely transparent "image"- i.e. no logo whatsoever. I can choose to style the image and re-size it, so it obviously thinks something is there...

Any tips on whether I should be using another format or something along those lines? I am importing the image via photoshop.

utnik

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Re: Importing images with transparency
« Reply #1 on: May 07, 2014, 11:02:30 pm »
hi karela

the usual (and better) format for a logo is a vector format (if you have one…)
but transparency should work with a .tiff file with a correct alpha channel as well.

what does 'importing the image via photoshop' mean?

utnik

Karela

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Re: Importing images with transparency
« Reply #2 on: May 08, 2014, 06:37:36 pm »
Sorry, "importing via photoshop" was a pretty unclear way to put it.

What I meant to say is that the organization gave me their logo as a jpeg with a background, I cut it out in photoshop so as not to have the background and saved it as a tiff. I could, however, save it as any of the other options that photoshop has on offer.

I am not familiar with alpha channels, I see that there is a box to check off when you save the document, but it is not possible to check it. What specifications am I looking for and where can I see/change them?

A vector would obviously be ideal, even though it  is relatively high resolution as is. Suggestions on how to create one would also be welcome.


utnik

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Re: Importing images with transparency
« Reply #3 on: May 08, 2014, 07:28:49 pm »
hi karela

…saved it as a tiff. I could, however, save it as any of the other options that photoshop has on offer.
i just checked – tiff with transparent background from photoshop (cs4) works well in scribus 1.4.3

Quote
I am not familiar with alpha channels, I see that there is a box to check off when you save the document, but it is not possible to check it. What specifications am I looking for and where can I see/change them?
check 'save transparency' in the 'tiff options' – should work well.

utnik

Nermander

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Re: Importing images with transparency
« Reply #4 on: May 09, 2014, 08:03:59 am »
Alpha channel is the transparency. Without alpha channel you have no transparency.

Note that some PDF formats can't handle transparency and Scribus does not yet include a transparency flattener (which would be needed to "simulate" transparency in those PDF versions). You need PDF 1.4 or later to get transparency.

utnik

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Re: Importing images with transparency
« Reply #5 on: May 09, 2014, 10:05:09 am »
hi nermander

Alpha channel is the transparency. Without alpha channel you have no transparency.

Note that some PDF formats can't handle transparency and Scribus does not yet include a transparency flattener (which would be needed to "simulate" transparency in those PDF versions). You need PDF 1.4 or later to get transparency.

all this is true for images with 'real transparency' (shades between 0% and 100% of visibility) – what karela does is just cutting out a logo. there's only 'fully visible' ar 'fully transparent' – no need of a flattener or a .pdf version higher than 1.3…

utnik

Nermander

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Re: Importing images with transparency
« Reply #6 on: May 09, 2014, 12:37:52 pm »
If an object surrounded by full transparency overlaps another object, isn't a flattener needed to "cut" the underlying object at the edge?

utnik

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Re: Importing images with transparency
« Reply #7 on: May 09, 2014, 02:48:26 pm »
If an object surrounded by full transparency overlaps another object, isn't a flattener needed to "cut" the underlying object at the edge?

no – just try it! (as long as there are no semitransparent parts it's like a simple cutting mask.)
the flattener is needed to calculate the color of semitransparent pixels (by mixing the semitransparent top color with the color of underlying objects…)

utnik

Karela

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Re: Importing images with transparency
« Reply #8 on: May 09, 2014, 06:27:24 pm »
Well, I did a lot of playing around and I seem to have "solved" my problem.

As I was looking over ALL the many options for saving a tiff, I saw one related to colour and remembered that I had not yet saved my image as cmyk and was planning to print (a side question, can you choose to put your scribus in either rgb or cmyk?).
Once I saved my document as cmyk instead of greyscale it worked without any problem.

I did tryouts with other greyscale transparent documents and they were also problem- warped, striped or just blank. Switching them to cmyk made them work.

utnik

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Re: Importing images with transparency
« Reply #9 on: May 09, 2014, 08:08:30 pm »
hi karela

…Once I saved my document as cmyk instead of greyscale it worked without any problem.

I did tryouts with other greyscale transparent documents and they were also problem- warped, striped or just blank. Switching them to cmyk made them work.

usually full transparency works well with .tiff files in rgb, cmyk and grayscale mode (at least on the systems i work: old win xp, mac os 10.9.2 and ubuntu 13.10) – my workflow is based on rgb and grayscale as long as possible. normally i don't convert to the final print profile before i generate the .pdf file. this prevents from dangerous cmyk to cmyk conversions and i'm free to change the output profile whenever i need to, without messing around with placed elements…

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…can you choose to put your scribus in either rgb or cmyk?

you don't have to. just place your elements in the best quality and do the conversion when you generate the print files – but:
  • avoid cmyk files with a wrong profile in color sensitiv projects…
  • for publications in grayscale it's better to convert the images to grayscale in an image processor – you have much more control over the different color channels…
utnik

cardioid

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Re: Importing images with transparency
« Reply #10 on: May 16, 2014, 09:37:28 am »
BTW, I just imported some graphics with transparency (a drop shadow) and used a .png file as my input. Seems to also work just fine. Then again, I have not output the document yet.

Stefan