BMP to PNG format

> Thanks for taking the time to check into this Rick. At least now I won't
> think it's just me going nuts.
>
> As a web person, the idea of using a BMP file instead of either a JPG or
> PNG just seems so unusual. I can't believe that Adobe is supporting that
> file format above the others so heavily in Captivate.
>
> I'd love to hear what the Captivate developers have to say about this.

What you should be comparing is the published file size, rather than the
size of your .cp file. The exact content of a source file is often rather
sketchy to all but the engineers, who often are not allowed to share their
dark secrets . :-)


As a general rule, PNG files use a lossless compression formula that gives a
smaller file size than standard bitmaps with no loss of quality. Standard
bitmaps don't have any compression formula applied, so they store one bit of
information (or byte, or word or whatever) for every pixel in the image so
the file sizes are generally larger than png or jpg which uses a lossy
'averaging' formula to compress images.

Generally speaking, in your source images you want to make sure they are
stored in as high a quality as possible, and only compress them when you
publish your files. So you are right to expect PNG or JPG compression on
published files, but Adobe are right to avoid compressing the source images.

Steve


--
http://twitter.com/Stevehoward999

Adobe Community Expert: eLearning, Mobile and Devices
European eLearning Summit - EeLS
Adobe-sponsored eLearning conference.
http://www.elearningsummit.eu

Hi,
Once PNG files are placed on the slide and merged with background, a bmp is created from the PNG image. Thus PNGs are not used on the slides.
Hence even if you are using PNG images as background, they are getting converted into bmp and hence the file size more or less remians the same.

Done a little test of my own. I have a 20 slide Captivate with audio that comes in at a huge 21.344KB. Then, just for a laugh I've removed unused files from the library (right click, select unused files, delete). The file size has dropped to 10413kb.

That's sliced it in half! The swf size is 1326kb.

What seems to happen is that Captivate copies A LOT of images, (and these are bitmaps so not compressed) and A LOT of the audio as it's working. It's like it uses itself (the.cp file) as a working directory.

Hope this helps.

AJ

Thanks for taking the time to check into this Rick. At least now I won't
think it's just me going nuts.

As a web person, the idea of using a BMP file instead of either a JPG or PNG
just seems so unusual. I can't believe that Adobe is supporting that file
format above the others so heavily in Captivate.

I'd love to hear what the Captivate developers have to say about this.

Marge


"Captiv8r" <captiv8r@kc.rr.com> wrote in message
news:g5b8mu$s20$1@forums.macromedia.com...
> Hi Marge
>
> I think the innards of the .CP file can be somewhat compared to the
> Twilight
> Zone. Here's why I say that.
>
> Your post aroused my curiosity. So I performed a small experiment. I
> created a
> blank Captivate project sized at 640 x 480 and containing 5 empty slides.
> Just
> to note file sizes.
>
> Next, I recorded using the same dimensions and ending up with 5 slides.
>
> Lastly, I exported the 5 background images from the recording, converted
> them
> to .PNG format and created a third project using the .PNG files as
> background
> images.
>
> The results are a bit on the odd side.
>
> CP file sizes:
> Baseline: 167 Kb
> Recording: 270 Kb
> Importing converted Backgrounds: 400 Kb
>
> SWF file sizes:
> Baseline: 58 Kb
> Recording: 78 Kb
> Importing converted Backgrounds: 80 Kb
>
> Image sizes listed inside .CP file
> Recording: 1201 Kb for each image. That's a total of 6005. So roughly 5
> Mb.
> Yet the .CP file is only listed as being 270 Kb for the same project. They
> must
> have one heckuva algorithm that compresses those bad boys.
>
> For the project using the converted .PNG images as backgrounds, each image
> is
> listed as being 10, 11 or 12 Kb. (There were 2 at 10, 2 at 11 and 1 at 12)
>
> I guess the lesson learned with Captivate is that 2 + 4 may actually equal
> 1.5
> or 25. Depends on how it's feeling at the moment.
>
> I'm guessing only one of the Captivate developers will be able to honestly
> answer what we may be seeing here. But it was a fun little exercise for a
> rainy
> Saturday afternoon in the midwest.
>
> Cheers... Rick
>

Hi Marge

I think the innards of the .CP file can be somewhat compared to the Twilight Zone. Here's why I say that.

Your post aroused my curiosity. So I performed a small experiment. I created a blank Captivate project sized at 640 x 480 and containing 5 empty slides. Just to note file sizes.

Next, I recorded using the same dimensions and ending up with 5 slides.

Lastly, I exported the 5 background images from the recording, converted them to .PNG format and created a third project using the .PNG files as background images.

The results are a bit on the odd side.

CP file sizes:
Baseline: 167 Kb
Recording: 270 Kb
Importing converted Backgrounds: 400 Kb

SWF file sizes:
Baseline: 58 Kb
Recording: 78 Kb
Importing converted Backgrounds: 80 Kb

Image sizes listed inside .CP file
Recording: 1201 Kb for each image. That's a total of 6005. So roughly 5 Mb. Yet the .CP file is only listed as being 270 Kb for the same project. They must have one heckuva algorithm that compresses those bad boys.

For the project using the converted .PNG images as backgrounds, each image is listed as being 10, 11 or 12 Kb. (There were 2 at 10, 2 at 11 and 1 at 12)

I guess the lesson learned with Captivate is that 2 + 4 may actually equal 1.5 or 25. Depends on how it's feeling at the moment.

I'm guessing only one of the Captivate developers will be able to honestly answer what we may be seeing here. But it was a fun little exercise for a rainy Saturday afternoon in the midwest.

Cheers... Rick