上次讲到了用DIB方法来获取图像的像素。从这次开始将如果运用已经得到的像素来处理图像。
图像插值放大的方法有很多，最主要的有二次线性插值和三次线性插值这两种。这次我把自己的程序中所用的二次线性插值的算法公布给大家，希望对各位要使用VB写类似程序的朋友有所帮助。
程序中用到的API、数据类型、全局变量的定义请参考上一篇：《VB实现图像在数据库的存储与显示》
Public Sub ZoomImage(ByVal OutPutWidth As Long, ByVal OutputHeight As
Long)
Dim I As Long
Dim L As Long
Dim X As Long
Dim Y As
Long
Dim Xb As Long
Dim Yb As Long
Dim Xe As Long
Dim Ye
As Long
Dim M As Integer
Dim N As Integer
Dim CurR As
Long
Dim CurG As Long
Dim CurB As Long
Dim NxtR As
Integer
Dim NxtG As Integer
Dim NxtB As Integer
Dim DR As
Single
Dim DG As Single
Dim DB As Single
Dim DRt As
Single
Dim DGt As Single
Dim DBt As Single
Dim Xratio As
Single
Dim Yratio As Single
Dim CurStep As Single
Dim NxtStep
As Single
Dim NegN As Single
On Error GoTo ErrLine
If Not
CanZoom Then Exit Sub
Done = False
OutPutWid = OutPutWidth -
1
OutPutHei = OutputHeight - 1
I = (Bits \ 8) - 1
ReDim
ColTmp(I, InPutWid, OutPutHei) '先从Y方向进行缩放处理，结果保存在此中间数组内
ReDim
ColOut(I, OutPutWid, OutPutHei)
Xratio = OutPutWid /
InPutWid
Yratio = OutPutHei / InPutHei
TimeZoom =
timeGetTime
NegN = 1 / Int(Yratio + 1)
For X = 0 To
InPutWid
CurR = ColVal(0, X, 0)
CurG = ColVal(1, X, 0)
CurB
= ColVal(2, X, 0)
CurStep = 0
NxtStep = 0
For Y = 0 To
InPutHei - 1
NxtStep = CurStep + Yratio
Yb = CurStep
Ye
= NxtStep
N = Ye - Yb
ColTmp(0, X, Yb) = CurR
ColTmp(1,
X, Yb) = CurG
ColTmp(2, X, Yb) = CurB
M = Y + 1
NxtR =
ColVal(0, X, M)
NxtG = ColVal(1, X, M)
NxtB = ColVal(2, X,
M)
If N > 1 Then
DRt = (NxtR - CurR) * NegN
DGt =
(NxtG - CurG) * NegN
DBt = (NxtB - CurB) * NegN
DR =
0
DG = 0
DB = 0
For L = Yb + 1 To Ye - 1
DR =
DR + DRt
DG = DG + DGt
DB = DB + DBt
ColTmp(0, X,
L) = CurR + DR
ColTmp(1, X, L) = CurG + DG
ColTmp(2, X,
L) = CurB + DB
Next
End If
CurStep =
NxtStep
CurR = NxtR
CurG = NxtG
CurB =
NxtB
Next
ColTmp(0, X, OutPutHei) = NxtR
ColTmp(1, X,
OutPutHei) = NxtG
ColTmp(2, X, OutPutHei) =
NxtB
Next
NegN = 1 / Int(Xratio + 1)
For Y = 0 To
OutPutHei
CurR = ColTmp(0, 0, Y)
CurG = ColTmp(1, 0,
Y)
CurB = ColTmp(2, 0, Y)
CurStep = 0
NxtStep = 0
For
X = 0 To InPutWid - 1
NxtStep = CurStep + Xratio
Xb =
CurStep
Xe = NxtStep
N = Xe - Xb
ColOut(0, Xb, Y) =
CurR
ColOut(1, Xb, Y) = CurG
ColOut(2, Xb, Y) = CurB
M =
X + 1
NxtR = ColTmp(0, M, Y)
NxtG = ColTmp(1, M, Y)
NxtB
= ColTmp(2, M, Y)
If N > 1 Then
DRt = (NxtR - CurR) *
NegN
DGt = (NxtG - CurG) * NegN
DBt = (NxtB - CurB) *
NegN
DR = 0
DG = 0
DB = 0
For L = Xb + 1 To Xe
- 1
DR = DR + DRt
DG = DG + DGt
DB = DB +
DBt
ColOut(0, L, Y) = CurR + DR
ColOut(1, L, Y) = CurG +
DG
ColOut(2, L, Y) = CurB + DB
Next
End
If
CurStep = NxtStep
CurR = NxtR
CurG = NxtG
CurB
= NxtB
Next
ColOut(0, OutPutWid, Y) = NxtR
ColOut(1,
OutPutWid, Y) = NxtG
ColOut(2, OutPutWid, Y) =
NxtB
Next
Done = True
TimeZoom = timeGetTime -
TimeZoom
CanPut = True
Exit Sub
ErrLine:
MsgBox
Err.Description
End Sub
全局变量定义：
Dim ColTmp() As Byte '用于保存插值中间变量
Dim OutPutHei As Long
'要插值的目标高度
Dim OutPutWid As Long '要插值的目标宽度
Public TimeZoom As Long
'插值运算使用的时间
|
