Centering texture

[Benalish]

Hello,
Since the widgets provided by the AceGUI library have their position locked, I rewrote the widget from scratch. In the final result, however, you notice that the lower and right sides of the background are less visible than the upper and left ones.
How can I make the four sides equal?




MWE:

local test = CreateFrame("Frame",nil,UIParent)
local backdrop = {
    bgFile = "Interface\\Buttons\\WHITE8X8",
    edgeFile = "Interface\\Tooltips\\UI-Tooltip-Border",
    tile = true,
    tileSize = 8,
    edgeSize = 16,
    insets = {
        left = 3,
        right = 3,
        top = 3,
        bottom = 3
    },
    
}
test:SetBackdrop(backdrop)
test:SetBackdropColor(0, 0, 0, .95)
test:SetSize(150,150)
test:SetPoint("CENTER")
 
local colorPicker = CreateFrame("Button",nil,test)
colorPicker:SetSize(24,24)
colorPicker:SetPoint("CENTER")
 
colorPicker.colorSwatch = colorPicker:CreateTexture(nil, "OVERLAY")
colorPicker.colorSwatch:SetWidth(19)
colorPicker.colorSwatch:SetHeight(19)
colorPicker.colorSwatch:SetTexture("Interface\\ChatFrame\\ChatFrameColorSwatch")
colorPicker.colorSwatch:SetPoint("CENTER")
colorPicker.colorSwatch:SetVertexColor(0, 0, 0)
 
colorPicker.texture = colorPicker:CreateTexture(nil, "BACKGROUND")
colorPicker.texture:SetWidth(16)
colorPicker.texture:SetHeight(16)
colorPicker.texture:SetTexture(1, 1, 1)
colorPicker.texture:SetPoint("CENTER", colorSwatch)
colorPicker.texture:Show()
 
colorPicker.checkers = colorPicker:CreateTexture(nil, "BACKGROUND")
colorPicker.checkers:SetWidth(14)
colorPicker.checkers:SetHeight(14)
colorPicker.checkers:SetTexture("Tileset\\Generic\\Checkers")
colorPicker.checkers:SetTexCoord(.25, 0, 0.5, .25)
colorPicker.checkers:SetDesaturated(true)
colorPicker.checkers:SetVertexColor(1, 1, 1, 0.75)
colorPicker.checkers:SetPoint("CENTER", colorSwatch)
colorPicker.checkers:Show()