Gary,
Compare sizes as I mentioned doing in your previous thread.
[Link: remotecentral.com]Pixel depth has the main affect on required memory.
The actual transparency setting has nothing to do with memory requirements. It's the images themselves that are either transparent or not (PNGs) versus BMP where transparency is either none or the color in the top-left corner.
For BMP files, you can have 1, 4, 8, 32 bit depth which is 2, 16, 256, and true color respectively. 1-bit gives 8 pixels per byte, 4-bit gives 2 pixels per byte, 8-bit is 1 pixel per byte, and 32 bit is 4 bytes per pixel. JPG files are treated as 32-bit images.
PNG files have 2 options, 32-bit and 8-bit. When exporting a PNG from most image programs, you can save as a palettized (format known as PNG-8) or as true-color image. To get the "Image Transparency" on the 7000, you must use an Alpha-Channel in your PNG images which means using true color (32-bit) . However, just because you use 32-bit does not mean that the PNG requires 4 bytes per pixel. PNGs are compressed and the algorithm used by the image editor and in PPENG dictates that size depends solely on the "complexity" also known as "image frequency". Image frequency increases when a color value from one pixel to the next varies greatly. The more variance, the higher the frequency.
Also note that filters such as "sharpen" will increase frequency. Blur filters are often used to decrease frequency. Too much to discuss here. If you are interested, read up on digital imaging concepts such as "frequency" from readily available sites such as
http://www.pinoy7.com for paintshop, etc...
So, prior to exporting a 32-bit PNG, you can decrease color depth and use dithering or nearest color methods to decrease frequency. Right before exporting, increase the color depth to 32-bit and then export with transparency. Increasing the color depth back to 32 does NOT increase the frequency. The end result will be that the memory requirement is typically smaller.
This post is not meant as an end-all be-all answer. However, as I mentioned before, you should spend some time comparing simulator file sizes as this is the BEST way to find out just how much an item takes.
Just to give you an idea of required memory for BMP files. A 240x261 image in 2 color (1-bit) requires about 9KB. Increase the number of colors to 16 (4 bits) and you go from 9KB to around 33-34KB. From 16 to 256 colors, you are looking at about 65KB per image. Then, for the person who just can't live with 256 colors and wants 32, they must realize that that same image will be around 256KB. Therefore, you can get approximately 4 images of this size per MB. Knowing there's only 28MB of usable space in the remote, that only allows around 112 imags of this size. These numbers are for BMP files. PNG memory requirements vary based on complexity and you MUST simulate to know exactly what memory an image requires. You simply compare sizes by simulating and then switching out images.
Hope this helps shed some light on the previously hidden info about image memory requirements. If you don't mind, please edit your post and change the subject line to "How much memory does an image actually require?".
Thanks,
Lyndel
