Using VK_IMAGE_TILING_LINEAR for srgb formats? - vulkan

Question

So I'm still trying to figure out color spaces for render textures, and how to create images without color banding. Within my gbuffer I use VK_FORMAT_R8G8B8A8_UNORM with VK_IMAGE_TILING to for my albedo texture AND VK_FORMAT_A2B10G10R10_UNORM_PACK32 with VK_IMAGE_TILING_OPTIMAL for my normal and emission render textures. For my brightness texture (which holds pixel values that are considered "bright" within a scene) and glow render texture (the final texture for bloom effects to be added later onto the final scene), I use VK_FORMAT_R8G8B8A8_SRGB and VK_IMAGE_TILING_OPTIMAL (although looking at this, I should probably make my bright and final textures R16G16B16A16 float formats instead). What I got was definitely not what I had in mind:
Changing the tiling for my normal, emission, glow, and brightness textures to VK_IMAGE_TILING_LINEAR, however, got me nice results instead, but at the cost of performance:
The nice thing about it though (and sorry about the weird border on the top left, was cropping over on MS paint...), is that the image doesn't suffer from color banding, such as when instead of using these formats for my textures, I use VK_FORMAT_R8G8B8A8_UNORM with VK_IMAGE_TILING_OPTIMAL:
Were you can see banding occuring on the top left of the helmet, as well as underneath it (where the black tubes are). Of course, I've heard of avoiding VK_IMAGE_TILING_LINEAR from this post
In general, I'm having trouble figuring out what would be the best way to avoid using VK_IMAGE_TILING_LINEAR when using srgb textures? I still would like to keep the nice crisp images that srgb gives me, but I am unsure how to solve this issue. The link might actually have the solution, but I'm not very much sure if there's a way to apply it to my gbuffer.
I would also like to clarify that VK_IMAGE_TILING_OPTIMAL works fine for Nvidia based GPUs (well, tested on a GTX 870M) but complains about using VK_IMAGE_TILING_LINEAR for srgb format, however, intel based gpus work fine with VK_IMAGE_TILING_LINEAR and sort of crap out like the first image up top this post when using VK_IMAGE_TILING_OPTIMAL.
The engine is custom made, feel free to check it out in this link
If you fancy some code, I use a function called SetUpRenderTextures() inside Engine/Renderer/Private/Renderer.cpp file, under line 1396:
VkImageCreateInfo cImageInfo = { };
VkImageViewCreateInfo cViewInfo = { };
// TODO(): Need to make this more adaptable, as intel chips have trouble with srgb optimal tiling.
cImageInfo.sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO;
cImageInfo.usage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT | VK_IMAGE_USAGE_SAMPLED_BIT;
cImageInfo.imageType = VK_IMAGE_TYPE_2D;
cImageInfo.format = VK_FORMAT_R8G8B8A8_UNORM;
cImageInfo.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
cImageInfo.mipLevels = 1;
cImageInfo.extent.depth = 1;
cImageInfo.arrayLayers = 1;
cImageInfo.extent.width = m_pWindow->Width();
cImageInfo.extent.height = m_pWindow->Height();
cImageInfo.samples = VK_SAMPLE_COUNT_1_BIT;
cImageInfo.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
cImageInfo.tiling = VK_IMAGE_TILING_OPTIMAL;
cViewInfo.sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO;
cViewInfo.format = VK_FORMAT_R8G8B8A8_UNORM;
cViewInfo.image = nullptr; // No need to set the image, texture->Initialize() handles this for us.
cViewInfo.viewType = VK_IMAGE_VIEW_TYPE_2D;
cViewInfo.subresourceRange = { };
cViewInfo.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
cViewInfo.subresourceRange.baseArrayLayer = 0;
cViewInfo.subresourceRange.baseMipLevel = 0;
cViewInfo.subresourceRange.layerCount = 1;
cViewInfo.subresourceRange.levelCount = 1;
gbuffer_Albedo->Initialize(cImageInfo, cViewInfo);
gbuffer_Emission->Initialize(cImageInfo, cViewInfo);
cImageInfo.format = VK_FORMAT_R8G8B8A8_SRGB;
cViewInfo.format = VK_FORMAT_R8G8B8A8_SRGB;
cImageInfo.tiling = VK_IMAGE_TILING_OPTIMAL;
GlowTarget->Initialize(cImageInfo, cViewInfo);
// It's probably best that these be 64bit float formats as well...
pbr_Bright->Initialize(cImageInfo, cViewInfo);
pbr_Final->Initialize(cImageInfo, cViewInfo);
cImageInfo.format = VK_FORMAT_A2B10G10R10_UNORM_PACK32;
cImageInfo.tiling = VK_IMAGE_TILING_OPTIMAL;
cViewInfo.format = VK_FORMAT_A2B10G10R10_UNORM_PACK32;
gbuffer_Normal->Initialize(cImageInfo, cViewInfo);
gbuffer_Position->Initialize(cImageInfo, cViewInfo);
So yes, the rundown. How to avoid using linear image tiling for srgb textures? Is this a hardware specific thing, and is it mandatory? Also, I apologize for any form of ignorance I have on this subject.
Thank you :3

Answer 1

Support for this combination is mandatory, so the corruption in your first image is either an application or a driver bug.
So VK_FORMAT_R8G8B8A8_SRGB is working with VK_IMAGE_TILING_OPTIMAL on your Nvidia GPU but not on your Intel GPU? But VK_FORMAT_R8G8B8A8_SRGB does work with VK_IMAGE_TILING_LINEAR on the Intel GPU?
If so, that sounds like you've got some missing or incorrect image layout transitions. Intel is more sensitive to getting those right than Nvidia is. Do the validation layers complain about anything? You need to make sure the image is VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL when rendering to it, and VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL when sampling from it.