Problems with file size after opening GIF files in ImageJ

[Marsilius Mues]

Dear All,

I have a problem when opening GIF files in ImageJ, but maybe someone can give me a hint: I want to make an AVI movie from a series of GIF files. The file size of each GIF file (325x258 pixels, 32 colors) is about 30 KB when checking them on my harddrive. However, when I open them individually or as a series in ImageJ, each file suddenly gets a size of 82 KB which makes the final AVI movie much bigger then intended. What is going on here and is there a way to keep the small size of only 30 KB for each GIF file in ImageJ?

Thanks a lot for your help!
Cheers, Marsilius

[Michael Schmid]

Hi Marsilius,

GIF files have only 256 colors (8 bits per pixel, not 24 bits like  
full RGB) and they are compressed using the LZW algorithm. LZW is  
very efficient if you have large areas of exactly the same color.
You can save an AVI with JPEG compression; you can set the quality in  
Edit>Options>Input/Output. Lower quality will produce smaller files  
but introduce more artifacts. You can also try PNG compression; this  
is non-lossy and has an efficiency similar to GIF. Unfortunately,  
many programs don't read PNG-encoded AVIs.

In case that a program cannot read your AVI files, you can also try  
to modify the image size: Some programs cannot read AVI files it the  
width or height is not an integer multiple of 4 or 8.

Michael
________________________________________________________________

On 15 Jul 2010, at 12:00, Marsilius Mues wrote:

> Dear All,
>
> I have a problem when opening GIF files in ImageJ, but maybe  
> someone can give me a hint: I want to make an AVI movie from a  
> series of GIF files. The file size of each GIF file (325x258  
> pixels, 32 colors) is about 30 KB when checking them on my  
> harddrive. However, when I open them individually or as a series in  
> ImageJ, each file suddenly gets a size of 82 KB which makes the  
> final AVI movie much bigger then intended. What is going on here  
> and is there a way to keep the small size of only 30 KB for each  
> GIF file in ImageJ?
>
> Thanks a lot for your help!
> Cheers, Marsilius

[Darren David Thomson]

Hi Marsilius,

I dont know if your intending to analyse after, but if you just want  
an avi that you can use in a presentation, then save as an animated GIF.

This file set was originally made for animators, you can actually drop  
the file into windows explorer and it will play straight off. But for  
presentations, just drop it onto powerpoint. Though i think there  
might be something else that you have to do to the file... cant think  
off th etop of my head what it is though sorry, try it out anyway.

Darren


Quoting Marsilius Mues <[hidden email]>:

> Dear All,
>
> I have a problem when opening GIF files in ImageJ, but maybe someone  
>  can give me a hint: I want to make an AVI movie from a series of  
> GIF  files. The file size of each GIF file (325x258 pixels, 32  
> colors) is  about 30 KB when checking them on my harddrive. However,  
> when I open  them individually or as a series in ImageJ, each file  
> suddenly gets  a size of 82 KB which makes the final AVI movie much  
> bigger then  intended. What is going on here and is there a way to  
> keep the small  size of only 30 KB for each GIF file in ImageJ?
>
> Thanks a lot for your help!
> Cheers, Marsilius
>
>

Thanks for you time,

regards

Darren Thomson
BSc Physiology (hons)
ID:s0971727

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