From some of the prior linked discussion, ATI seems to have indicated that changes result from some analysis of the textures. Also, the role of texture stages in this is left unclear (from my understanding of the article), and it isn't even clear to me whether texture stages greater than 0 are upgraded to brilinear from bilinear in control panel AF (this would support at least that there is some general case analysis). The way the difference method is described, it sounds like it would respond to the slightest change in any texture layer that has any more than "zero" impact on the output color the same as that change in all texture layers. From this, a colored mip map level could "erase" differences in color that might be there in other texture layers by pushing them into bits lost due to error (but perhaps not, or less often, if it was applied like the "transparent" option in the D3D AF tester in a program).
Given the difference to 9800XT, and the benchmark results, this, however, seems irrelevant to whether the X800 is 1) getting a performance benefit from this ocurring with Application Preference selected 2) producing something different....it is just relevant to removing doubt about what the differences are doing to image quality.
Where the article fails, and what Wavey seems to be discussing I think, is in evaluating the image quality significance of the pixels marked by the difference methodology they are using. The problem with the difference method used (as I understand it) is that the magnitude of difference isn't represented at all. Some extra work could have clarified this fairly simply, like, as one example, comparing known "all brilinear" to "what we believe is brilinear" with the same compare method. This would have ruled out something like a significant departure in methodology whose differences might be misrepresented by the compare method (i.e., things like fast trilinear and "gamma adjusted" edge sampling can achieve better or equivalent image quality while being different). It would be nice if Wavey could have access to the tool to evaluate this.
However, this does not make the article necessarily erroneous and misrepresentative, like some prior "cheating" articles have been, because it would require the above significant departure from expected methodology for the differences shown to be something different than what the article proposes. ATI hasn't explained such a departure in methodology, so the article seems quite reasonable, as does the conclusion of cheating. All it means is that we don't have the clarity we could have had at the moment.
Given the difference to 9800XT, and the benchmark results, this, however, seems irrelevant to whether the X800 is 1) getting a performance benefit from this ocurring with Application Preference selected 2) producing something different....it is just relevant to removing doubt about what the differences are doing to image quality.
Where the article fails, and what Wavey seems to be discussing I think, is in evaluating the image quality significance of the pixels marked by the difference methodology they are using. The problem with the difference method used (as I understand it) is that the magnitude of difference isn't represented at all. Some extra work could have clarified this fairly simply, like, as one example, comparing known "all brilinear" to "what we believe is brilinear" with the same compare method. This would have ruled out something like a significant departure in methodology whose differences might be misrepresented by the compare method (i.e., things like fast trilinear and "gamma adjusted" edge sampling can achieve better or equivalent image quality while being different). It would be nice if Wavey could have access to the tool to evaluate this.
However, this does not make the article necessarily erroneous and misrepresentative, like some prior "cheating" articles have been, because it would require the above significant departure from expected methodology for the differences shown to be something different than what the article proposes. ATI hasn't explained such a departure in methodology, so the article seems quite reasonable, as does the conclusion of cheating. All it means is that we don't have the clarity we could have had at the moment.
?
