# Quality of Graphics3D primitives in GIFs (V11)

Bug introduced in V11.1 and fixed in V11.2

What happened? Is this a regression or maybe some default options were changed?

Test case:

Graphics3D[Sphere[]] // Export["Test.gif", #] &


Comparison 11.1.1 vs 10.4 on Windows 10.

• Eek... any impact on the file size? – Yves Klett Aug 21 '17 at 8:34
• @YvesKlett FileByteCount /@ {"11.gif", "10.gif", "11.png", "10.png"} -> {18493, 28635, 41518, 42317} – Kuba Aug 21 '17 at 8:35
• About the file sizes: Dithering introduces noise to smoothen the appearance of gradients. Noise doesn't compress well. I would expect a dithered GIF (containing smooth gradients) to be significantly larger than a non-dithered one. If it weren't for @ChipHurst's comment I would say that the reason to change Automatic to non-dithered could only be file size reduction. – Szabolcs Aug 23 '17 at 12:01
• @Szabolcs That would have been my guess too. – Chip Hurst Aug 23 '17 at 20:45

I talked to the relevant developer and it turns out this is indeed a regression.

It looks as if the default "DitheringMethod" changed from "FloydSteinberg" to None.

Compare "DitheringMethod" pointing to None, Automatic, and "FloydSteinberg" in 10.4 and 11.1:

Table[Labeled[
ImportString[ExportString[Graphics3D[Sphere[]], "GIF", "DitheringMethod" -> d]],
{$VersionNumber, d}, Top], {d, {None, Automatic, "FloydSteinberg"}} ]  In 10.4: $VersionNumber

10.4

Equal[
ImportString[ExportString["Graphics3D"[Sphere[]], "GIF"]],
ImportString[ExportString["Graphics3D"[Sphere[]], "GIF", "DitheringMethod" -> "FloydSteinberg"]]
]

True


In 11.1:

\$VersionNumber

11.1

Equal[
ImportString[ExportString["Graphics3D"[Sphere[]], "GIF"]],
ImportString[ExportString["Graphics3D"[Sphere[]], "GIF", "DitheringMethod" -> None]]
]

True

• Was that intentional? – Kuba Aug 21 '17 at 14:49
• I don't know. Just something I observed when looking through the export options of GIF. – Chip Hurst Aug 21 '17 at 14:50
• Thanks. Is anybody around you could ask or should I ask support? :) – Kuba Aug 22 '17 at 6:54
• I talked to the relevant developer and it turns out this is indeed a regression. – Chip Hurst Aug 23 '17 at 3:26
• Thanks for forwarding it. – Kuba Aug 23 '17 at 5:33