FLASH: Bitmap Images and JPEG

[John Croteau]

Hi Brett and all,


1) Do not compress with JPEG or any other Lossy compression file format

before importing into Flash. Any file size reduction (lossy or lossless)

of a bitmap before a file is imported into Flash that is not based on

the height and width of the file is not reflected in Flash. Compression

artifacts created by JPEG compression are often not handled well in

Flash. Use non-lossy import formats such as .bmp, .pict, .png or gif

whenever possible.

2) Don't expect the same compression and quality of JPEG compression

that the newest versions of Fireworks, Photoshop can provide. Flash is

primarily a Vector program and generally works better with vectors than

bitmaps.

3) Flash's jpeg compression can cause banding in fine bitmap gradients.

4) Reduce noise and unnecessary details in the original bitmap before

importing into Flash. Reducing colors or doing manual fills on the

original are examples that can improve the final quality/size of the

exported bitmap in Flash. By reducing the noise and unneeded details you

will likely reduce the jpeg file size Flash creates on export. Also it

may allow you to reduce the JPEG compression setting to reduce file size

or increase it to obtain a better picture quality while not being too

big.

5) Crop the Bitmap before importing into Flash. Flash exports the whole

bitmap whether you use all of it or not.

6) Flash allows customizing of individual bitmaps and whether they are

exported as lossless or JPEG and at what JPEG Quality. In the Library

under Properties change the Export as: option from Default to customize

an individual bitmap's export characteristics. Jpeg Compression

available when exporting is 0-100. 100 is the highest quality but does

not mean no loss.

7) Note, the Lossless compression is similar to PNG compression. Use of

Lossless does NOT necessarily produce larger files, sometime Lossless

will produce smaller files.

8) Try turning off Allow Smoothing to see how the bitmap will look with

smoothing disabled. This is a checkbox also in the Library under

Properties.

9) Generally use the Web safe colors for large flat areas of colors.

This will result in browsers, operating in 256 color mode, to be less

likely to

dither or change the color of these large areas.

10) Bitmap quality can be affected by the overall Movie Quality setting.


As you can see there is no one answer for getting good acceptable bitmap

quality in Flash.


-----------                               -----------------------

John Croteau

croteauerols [dot] com (mailto:croteauerols [dot] com)

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