Ok. We can do texture maps as bitmaps or tif files. Or jpg and a few others but the disadvantages there are obvious. For bitmaps and tif files what reasons are there for choosing one or the other? What do they each offer us in terms of texture mapping?

.TIF files take up much less disk space.

Arcady- JPEGs offer by far the most compression, but they are also what is called a lossy (not lousey) format- there is some degrading of the image. Most other formats offer optional LZW compression, the same type used in a ZIP file, which will typically only compress a photo about 25 to 40% (but does a lot better on areas of solid color). Compressed BMPs are very rare (but it is in the spec), other than that it is a toss up, a LZW compresssed TIF is about the same size a compressed Photoshop file or whatever. I use Photoshop format on most all the stuff on my computer, but I have 24 GB of disk space, I put the textute maps of the file I put on the web as JPEGs. There is also the new PNG format, but I haven't used it, some have said it is non-lossy and compresses better than LZW, I don't know that for sure.

Personally I would suggest people start posting their texture maps as bitmap or tif files. Most jpg files are so distorted as to be virtually unusable. They make for a decent web display format but not for using in work. I for one would be willing to wait the extra time to download a bitmap or tif over a jpg. I'd also not mind their being less texture files out there due to disk space limits if those out there were of higher quality. I see some great renders from the photo realistic textures but only from the authors of those textures. By the time the jpg versions get out to the rest of the world they have solid blockly color seperations and blurs. So then the only issue is weather there are any differences in quality and what you can do with them in terms of bitmaps and tifs. For those trying to decide what format to use locally for their own textures. I'm gathering there really isn't much difference if any.

Arcady: Posting .TIFF files is not a good idea, especially if they originated from a Macintosh computer using PhotoShop. I have yet to see a Windows program that will recognize the file format (except, perhaps, hijack). JPEG files can be saved in one of 10 compression settings and 7 through 10 give very little image quality loss yet yield good compression figures. Since Poser 4 (at least the Mac Version) will read jpeg files directly, this would seem to be the ideal cross platform format for us all to use (as long as the person originating the file doesn't use the lower numbers on the compression scale). Hope this clears things up a little for you. BTW the Mac version will also read BMP formated files directly.

Actually I was just editing a tif on my PC in both paint shop pro and photoshop (I switch back and forth). I always thought tif was a natice PC format and was suprised to find it available on the Mac as well. All of the image editors I use on both my PC and Mac save jpeg's in terms of percentage of loss or percentage of non-loss rather than a flat 1-10 scale. What are you using to image edit? Even at 0% loss/100% image the jpg's don't look as good as the tif's, bmp's, psd's (photoshop), cpt's (corel), png's (fireworks) or psp's (paint shop pro). I don't have painter on either machine and corel's only on my PC (is there even a mac version?). I've yet to look at a p3d file in a flat display to compare it but I would assume the same. the jpg routine is a lossy one and there is always some level of degredation. By the way the tif I was working on was saved on my MAC in photoshop using the MAC setting for a tif and then opened on PC. Saved in photoshop and later opened on the PC in both paint shop pro and photoshop. JPG's compress well. I use them in my webwork when I need small files with more than the 216 websafe colors. But I never make a statement of quality or color purity behind them. They're just too lossy for it.

If you have never done it, I suggest you pick a nice sharp ray-traced render and compress it in various JPEG compressions, then reopen the images and also compare file sizes. JPEG does amazingly well, it mostly suffers in hard edges, there are little artifaces around them- but most texture maps aren't all that critical on edges, anyway. I often use 1500 x 1500 texture maps, that would over 6 Mb raw filesize, probaly about 2-3 Mb as a Zipped tif, who is going to set through downloading that on a modem? A high quality JPEG will be only about 300K. One thing to remember though, don't use JPEG internally, just for sharinging files. If you keep reopening, modifing and resaving the file in JPEG the degradation keeps adding up. Incidently, I've never seen any modern program on the PC or Mac that had trouble with TIF, there is a option for Mac or PC byte ordere in Photoshop (has to do with LSB first), but there is also a flag in the file for the byte order, so it shouldn't make any difference what you pick.

In reference to your question concerning which image editor I'm using -- it's Photo Shop 5 (same for V 3.0 and 4.0) and Painter 6.0. I even tried to open one of the Mac Photo Shop TIFF images in the Windows version of Photo Shop 5.0 and it wouldn't recognize it. I think the main problem has to do with the way the Mac handles resource files, but I'm not sure -- it's only a guess. I do know that the Windows programs take the photo Shop JPEG files with no problems. The 1 to 10 scale is the way Photo Shop 5.0 (at least on the Mac Version) handles it. And yes, I do specify PC byte order and have tried it with and without LZW compression. The programs I've tried in Windows are: PC Paint Photo Shop 5 MS Word (import picture option) The files were saved onto a CD Rom in ISO 9660 format (a standard Windows format). I also tried it with a Syquist EZ 135 cartridge and a 3M floppy disk which was pre-formatted for Windows by the manufacturer. If anyone has any suggestions, I'd love to hear them and would be more than willing to try them out. Jim Moore (jnmoore@usaor.net)

jmoore: that's interesting as I have photoshop 5 and 5.5 on both my PC and my MAC and I can use both forms of tif (PC and Mac) on both machines with no problems. I can also open the tif's in poser 4 on both the Mac and the PC. The tif's open in every graphic app I have. photoshop 5 does have a 1-10 scale. 5.5 has a full blown 1-100% scale for both jpg and gif (it's the only app out there at present that can make lossy gifs). To transfer files between the two I write them to a CD-RW in ISO 9660 format (I have CD-RW drives on both machines). On the perfect pitch question... No. I do work in a graphic design shop so I consider proper color to be important. What I see on the jpg's is banding. Where there are solid lines that mark off where it transitions from one color to another. On many of them it's as pronounced as the color line where the bottom green bar meets the right vertical green bar on the bottom of pages here on renderosity. Oh and would I download a 2-3 mb zipped tif? I already download character files of that size. So yes. I'd tolerate the extra wait for the quality improvement. The big issue is getting web space on servers to store those files.

I use .BMP for the texture maps in my models. OK, the files are big, but in zipping they compress spectacularly (since they are only black and white). If I JPEG such a file, oh yes, here come the diffraction-type fringes along the borders between the colors. - Also: I wrote a 2D graphics handling program, and when I put JPG support in, the JPG matter's source code is enormous. GIF support code is much shorter.

Also, if I render on a white background to use as a 2D cut-and-paste, if I JPG it, much of the white background near the image becomes that annoying few units darker than proper white (red=green=blue=255) and the 2D graphics program has trouble telling what is background and what is image. One way round that is to put along with the picture another picture which is white for background and black for image and, GIF-code it. - I remember handling a JPG'ed photo of an alien in a wood from a Gerry Anderson UFO site: when I came to extracting the alien, the alien's spacesuit is red, the forest is mostly green:: easy:: except that along the edge of the alien, the JPG process had made an annoyingly wide border of intermediate fawn and russet pixels, and I had to put into my 2D graphics program a special border-sharpening facility.

I'll agree with Allerleirauh on that pet peeve. I hate having to cancel out over and over as it looks for each texture. Writing them down as I go, then opening up all the jpgs and saving them as whatever. I also use tif's on my win 98 machine fine. :) Odd that some people would have trouble there. To: Buck: are you aware that using gif support s illegal now without a heafty license fee to Unisys? http://slashdot.org/articles/99/08/29/0722236.shtml

To Buck: On that render with white background problem. My poser manual suggests making a render using silhouette mode and bring that and your actual image render into a 2D app to make a mask to rip out the background with. Of course that won't work for your downloaded alien pic. For that you need photoshop 5.5's new background stripping features.

The main reason to use tifs is the Alpha channel. Png is a much better format then jpg..Just my 2 cents.. ARADTech

Bongo-sarong: I was careful to use ".tif" as I am well aware that Windows needs the extension since there is no internal resource file, HOWEVER I did not try spelling it different ways (it never occured to me, or to my friend who has the PC). I'll have to try that and see if it helps. Thanks!