mask size, memory and render time

[Dune]

I did a little test to see whether small or large masks had any influence on render times and memory consumption. In the chart you'll see that it doesn't really. I would have thought a 1.5 Mb JPG would use less memory than a large greyscale TIFF, LZW compressed. At first I even used 40Mb RGB psd files (TG didn't load greyscale psd), but wrote them off since today.
I did this because I have to produce a large render (a real blow up of 2x2 meters), and had to include many roads. They were a bit soft in my first tests, so I wanted to use a 200% mask, and thus sharpen the outcome. As far as this test goes, it should work ok this way, with no setbacks in memory use and rendertime. The only positive thing of a compressed JPG is that it takes less space on the HD. The quality is quite the same as a full TIFF, I looked at this in detail.
Does anyone have similar or other experiences with small versus large masks? Are my assumptions right?

[Hetzen]

That's an interesting question Dune. Something I'm working on uses 8k masks and have taken the assumption that what ever format the image file is, it still needs to be uncompressed, so have gone with .bmp files. So far I haven't hit a memory wall.

[Walli]

all textures and masks you use have to be accessed uncompressed during rendertime. So it doesn´t help to use a jpeg, as the information will be uncompressed. Sometimes its even worse when using compressed formats, as uncompressing can take time and also memory.

So as long as hard disk space is no issue, I always go with uncompressed formats.

[Henry Blewer]

I use PNG often, when I have to. I'll have to try bitmaps...

[jo]

Hi Dune,

As Walli says all image formats are uncompressed at load time. An uncompressed image ( TIFF perhaps ) and a compressed image ( JPEG perhaps ) will take the same amount of memory once loaded. From a quick look it seems a lower bit depth image will take less memory. If you have a greyscale mask you would be better off saving it as 8 bit greyscale TIFF rather then 24 bit RGB TIFF, for example.

Regards,

Jo

[Dune]

Thanks for your reactions. I figured compressed files would have to be decompressed by TG, so I'll stick to uncompressed greyscale from now. But there's hardly difference between the 8k and 2k masks as well, so I might as well use large masks for more detail (if necessary)...

[Walli]

by the way, would be nice if TG at some point could read in pictures on the fly ( as option), so that even with giant textures no memory problems occur. I think for max there has been a plugin which did that.