Invisible Backgrounds

Got some static images (jpeg + tiff) that I need to float over a video clip, playing in the background?

I can do the transparent white or black (depending upon the static image background) but it also takes out some of the objects' white and black (obviously!)

Though I could do it using an alpha channel - but I cant seem to?.. :confused:

Any chance of a step by step guide on how to take an object in an image (jpeg or tiff or psd) and make the background (whatever colour) transparent - without affecting the object? It?s late, and I think I'm missing something somewhere?. (probably brain cells?.)

Thanks

S

can you send me your image, or post it here.
So I can check it?

only tiff's get transparency correct, but in photoshop - when you save - there are 3 different settings dialogs that have 'transparent' settings, its a bit confusing.

i just changed the attachment file size limits and added the 'tiff' extension

Looks like there are a couple of issues here,

The main one seems to be photoshop files import with pre-multiplied alpha - which means they look a little wierd.
But tiff files dont which means they composite OK in catalyst.

I have created and tested a few files.

1. Transparent text in photoshop - you have to remove any pixels in the background layer.
2. Transparent text in photoshop saved as a tiff with the setting in the last attachment
3. A blob or brush painting saved as a photoshop file
4. A blob saved as a tiff
5. text photoshop composite in pixelmad shows fringing meaning its pre-multiplied - not quite right
6. text tif composite doesnt show fringing
7. blob photoshop comp shows fringing
8 blob/tif comp doesnt.
9. tiff settings i used, showing transparency setting.

Quote:

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Originally Posted by Mr_P

(jpeg + tiff)
S

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I dont know anyway of making a transparent jpeg - but i could be wrong.
Maybe jpeg 2000? but the performance of jpeg 2000 used to be terrible in quicktime

http://www.jpeg.org/

http://www.jpeg.org/jpeg2000/index.html

To take a pre-existing object or photograph which has a background you want to remove -use the extract filter in photoshop.

The extract filter takes quite a bit of experimentation.
You are going to have to read the manual on how to use this

But i took this image of some flowers and made the blue sky transparent.
You have to hand draw around the edges to help the filter, the 'smart hilighting' check box helps enormously. i used a big brush size to outline the edges. your brush size will depend on the resolution of the images.

the nicest thing about extract is that you dont have to be too accurate! just broad brush strokes, in close to the right place.

Richard -

thanks for the info - I've got it working now...

I created a blank document in photoshop with a transparent background.
Then used the magic mask tool to select the white areas in my graphic, then inverted the mask to select my object and copied it in to my new transparent document.
Saved it as a tiff, with the settings suggested - and it works brilliantly, with no need for transparent colour effects. - Object floats over background with no noticeable distortion

One of the issues I had was that I was using coreldraw (PC) to create the tiffs - and it doesn't save transparent backgrounds, although tiff format supports them... Basically it was merging the transparent with white... hence no transparency seen.

Got a bit of work to do converting all the relevant tiffs - will try your second method mentioned.

However, I can still use transparent white or tint colour effects for making simple text graphics on white backgrounds transparent :)

Thanks for the help

S

If you have a lot of images a mac program like graphic convertor will batch convert an entire folder - if setup correctly.

( there may be other programs that do this... )

http://versiontracker.com/dyn/moreinfo/macosx/11559

Quote:

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Originally Posted by Mr_P

Then used the magic mask tool to select the white areas in my graphic, then inverted the mask to select my object and copied it in to my new transparent document.

S

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when you have a complex image to separate with complex edges and ambiguous boundaries, using the extract filter is much better than using the magic mask.

Quote:

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Originally Posted by samsc

when you have a complex image to separate with complex edges and ambiguous boundaries, using the extract filter is much better than using the magic mask.

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There are several nice apps if you spend some money to give you very good result when extracting or masking you pictures.Timesavers!

Extensis Mask Pro is cool:
http://www.extensis.com/en/products/...=en_US&id=1018

Quick message to say thanks for all the info - just finished the fashion show and all went well - got all the required images invisible using a mix of all the suggestions...

Got some good results with inverse tint too - but a little bit stuttery on some playback... where invisible white or black didn't as much...

Quote:

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Originally Posted by Mr_P

but a little bit stuttery on some playback...

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how many layers?

what discs?

Which computer?

where you using your g4 with the delta audio card?

Using 1 x layer as animated background - cloud loop (feedback video - 006 SD_Cloud010.mov)
+ 1 x layer as tiff object with either embedded invisible background (see attached) or invtint on the white background (depending upon picture) - object then moved from L to R of screen with x,y posn
(ie a shoe flying through the clouds!)

Noticed a slow down of the background as the 'shoe' moved across the screen - normal playback resumed as soon as the shoe disappeared

Using a G5 2G mac with 2GRam - clean up-to-date hired machine - think it was a SATA drive, but might have been a fast SCSI one (wasn't my G4! - I only use it for pre-production)

Incidentally - are there any issues concerning xfade between a PAL and NTSC clips? Is it recommended to stick to one format - or doesn't it matter?

Quote:

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Originally Posted by Mr_P

Using 1 x layer as animated background - cloud loop (feedback video - 006 SD_Cloud010.mov)
+ 1 x layer as tiff object with either embedded invisible background (see attached) or invtint on the white background (depending upon picture) - object then moved from L to R of screen with x,y posn
(ie a shoe flying through the clouds!)

Noticed a slow down of the background as the 'shoe' moved across the screen - normal playback resumed as soon as the shoe disappeared

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this image isnt huge - there should not have been any change in graphics speed.

Quote:

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Originally Posted by Mr_P

Using a G5 2G mac with 2GRam - clean up-to-date hired machine - think it was a SATA drive, but might have been a fast SCSI one (wasn't my G4! - I only use it for pre-production)

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Disc speed wont make any difference if all you had was a still moving over an animated background.
Is that all you had?

Quote:

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Originally Posted by Mr_P

Incidentally - are there any issues concerning xfade between a PAL and NTSC clips? Is it recommended to stick to one format - or doesn't it matter?

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None issues whatsoever except they are slightly different sizes, and in the real world the pixel aspect ratio is different. NTSC and PAL might have different native gammas.
NTSC is 720x480 PAL is 720x576
as far as catalyst is concerned it doesnt matter. I dont take any notice of the frame rate.

Quote:

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Originally Posted by Mr_P

Noticed a slow down of the background as the 'shoe' moved across the screen - normal playback resumed as soon as the shoe disappeared

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You can use the statistic HUD to see if there any slowdowns.

The three values at the bottom summarise performance.

Movies- if your movie value approaches 100% - you are doing too much with your discs. Low values are good.
Graphics - if you are drawing too many things will approach 100%. Low values good.
Timing - accuracy of playback based on overall timing. 100% is good.