Topic awaiting preservation: transparent background for photos (Page 1 of 1)

Hi,

Is there anyway I can make a picture's background ( an object on a coloured background or something ) transparent without losing the quality of the image ? not gif format because it ruins everything !

Does anybody know if there is a function or command in photoshop for example, that creates an effect similar to the chroma key in cinematography for photographs?

Bye , bye !

You can use the PNG format. Press ctrl + alt + shift + s to save for the web, select PNG 24, be sure to check that transparency is on and save your file. The filesize will probably be huge though.

The PNG format even allows partial transparency contrarily to GIF, although it isn't fully supported in Internet Explorer.

----
If wishes were fishes, we'd all cast nets.

What is the intened use of the photo?

Whether or not an image has transparency depends a great deal on where/how it is being used...

I am interested in printing this photos .

I have tried also with the png but the quality of the photo is lost ( for the web this solution could work).
You understand that for printing I can not accept the quality of a transparent png .

I was searching some information about the Chromakey photography or something like this : how can I remove the coloured background of a photo ( whether exists a specific color like in cinematography which can be removed then, and how?)

You might want to check out this link regarding types of transparencies used for specific output.
Chroma key is a technique used in video, keying out a blue or green screen (background), so that the clip can be overlapped into another clip, which will allow the second clip to show through as the background..
similar to Rotoscoping.
Usually a video editing suite such as Adobe Premiere will produce it, but I am sure PS and the gurus here will know how to help you.

http://graphicssoft.about.com/cs/faq/a/transparency.htm

try this also for clipping paths
http://desktoppub.about.com/library/weekly/aa121302a.htm

cheers



(Edited by kromaZ on 08-26-2004 15:21)

For print you have a few options and it depends on what application and type out output device you are using.

A. Create a Clipping Path, this is a special path defined as a clipping path in photoshop or selected with in the publish application for use as the Clipping Path. Clipping paths are supported in either EPS, EPS/DCS, and TIFF formats.

B. If you application supports alpha channels, you can generate a Mask, save it as an extra channel (an Alpha Cannel) and save the image as a tiff or other supported file format. I believe Pagemaker 7+ would allows this option. An Quark 4+ will allow you to choose an the alpha to generate a clipping path.

C. If you are lucky enought to be going to Indesign, it supports transparancy and layers in Photoshop's native PSD format. All you have to do is place the PSD and choose the proper transparancy flatting level from options before printing.

Keep in mind transparecy in most desktop publishing only allow for monotone transparency. That is to say the background is either transparent on not transparent. Generally there are no in between levels. Which is way clipping paths are perfered for masking as a clipping path is rendered at the RIPs linework resolution giving you cleaner edges as opposed to a alpha channel mask that is render at the images resolution.
InDesign is the exception, as it will allow you to use transparency, which is flattend buy it's preprocessor just prior to printing giving you effective transparency.

As for chroma keying there is the photoshop Filter-->Extract and Selection-->Color range tools. But I perfer to do most of my masking by hand with quickmask or the pen tool.

I find I waste more time cleaning up auto generated masks then if I simply did it by hand. I have tested all the auto mask generation plug-in and I found non of them realy cost effective and still involving extensive clean-up.

For diffucult masking tasks, You might look up a technique called density masking or channel masking. This technique works well for masking smoke, leaves, and hair

(Edited by jstuartj on 08-26-2004 17:43)

Ok, possibly a stupid question - Are you printing jsut the photos, and want the background to be the color fo your paper? Or do you need them to be transparent on top of a background of some sort?

If you're just printing the photos, then simply leave the background white and save in whatever format you like.

If they need to be transparent over a specific background, then again - it depends on what it needs to interact with, and what app you are laying it out in......

The more specific you can be, the better help you'll get

zizucu: What resolution are the images your working with? From what your saying it sounds as if you may be working with low resolution images.

Depending on the printer your using, the images need to be scanned at 150 to 300 dpi (maybe higher). Before we can discuss how to make the images look better we need to know more details of the images.

-- not necessarily stoned... just beautiful.

The photos are at 180 ppi and have 2048/3072 pixels. I want to change the background of a picture for instance I have the model on a green background and I want to put a landscape behind it . It should be a kind of composition, so both the model and the new background will be printed.
The resolution of the printer is 300 dpi.

Ah-hah! So you don't want a transparent background in your FINAL picture, you want your model photo to lose the green you shot her/him on so he/she can be put into another setting. Right? The final image would have the new background. Right?

So it's layer time for you. Read this for starters:
http://www.gurusnetwork.com/tutorial/replace_background/

Ok - I thought we were going down the wrong path here

Transparency is not what you are looking for...you are looking to - as Steve so aptly titled his fantastic tutorial - Replace the background.

I highly recommend reading through the tutorial - it should give you exactly what you need.

You could use tiff with clipping paths. The replies before me provide all the info needed so I won't repeat them.