jefferson Posted July 20, 2003 Share Posted July 20, 2003 Hi I have always been led to believe that when saving renderings, a tif file would be better quality than a jpg. Not only that, but it would allow me to include an alpha channel. I have recently saved a rendering to both outputs, but upon close inspection (and I mean at 1600% in Photoshop) it appears that the jpg image allocates a more varied array of colors to surfaces than the tif. Where the tif uses just one color for an area, the jpg has at least two dozen. If the tif is better quality, shouldn't it have the same or more colors in it than the jpg? If anyone can clear this up for me, your posts will be gratefully received. Cheers, Link. Link to comment Share on other sites More sharing options...
Ernest Burden III Posted July 20, 2003 Share Posted July 20, 2003 jpeg is 'lossy' compression--meaning it will lose data to make the file smaller. It does so in a very advanced manner, but you lose stuff and it never comes back. If you do edge-detecting or motionblur filtering in Photoshop you can sometime reveal the flaws in a jpeg. A tif file is lossless. It can be compressed through Photoshop using jpeg compression (what's the point?) but normally is only compressed use an RLE (run-length encoding) method--no data loss. Normally tif would NOT carry an alpha mask/channel. That is usually the job of tga (Targa) files, but they must be saved to 32 bit to create the extra channel. 3D software can save a mask as a seperate tif file, just to make this more confusing. You would load it into a Photoshop file as a new channel. Now--if you have saved a tif in 16 bit color, it will appear to not be as good as a jpeg. But saved in 24 bit it is the only filetype that matters. Link to comment Share on other sites More sharing options...
jefferson Posted July 20, 2003 Author Share Posted July 20, 2003 Even with both the tif and jpg images saved at 24bit, the jpg has more defined colors than the tif. Is this expected? It looks like the jpg is higher in quality, despite the lossy compression, so should I stick with that or would you recommend the tif? Cheers, Link. Link to comment Share on other sites More sharing options...
Crazy Homeless Guy Posted July 20, 2003 Share Posted July 20, 2003 can you post a link to the images you are talking about? Link to comment Share on other sites More sharing options...
jucaro Posted July 20, 2003 Share Posted July 20, 2003 Hi Jefferson, The 'dozen' colors you see on a JPG upon close inspection (1600% zoom)is the result of the 'lossy' compression. This is how the jpg file algorithm compensates for the data loss that, in such a way it fools the eye that it is seeing a certain tonal value or color range Lets say that, in a JPG format file, a group of pixels at 100% zoom rate represents a certain color range. While in a TIF file, that same certain color range is represented NOT in a bunch of different colored pixels but rather the actual color. JPG files are best used if you are not going to do anymore significant editing on the picture Link to comment Share on other sites More sharing options...
jefferson Posted July 20, 2003 Author Share Posted July 20, 2003 Jucaro Great explanation. Thanks to you and everyone else for your help! Much appreciated. Cheers, Link. Link to comment Share on other sites More sharing options...
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