vb.net 从数据库读取图片循环显示

假如b窗体是form2,在a窗体中调用B窗体，直接dim frm as new form2,然后frm.show()就OK

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vb.net 图片显示问题，图片显示不出来

可能的原因是图片路径问题,路径用的相对路径,不要用绝对路径.

VB.NET中如何使两个PictureBox显示指定相对应的图片？

用一个全局变量保存这个1.jpg，如变量a，你按按钮2时，可以简单的在a中插入一个"A"，如a.SubString(0, a.Length-4) "A" a.SubString(a.Length-4)，这样就能把例如"C:/Images/1.jpg"变成"C:/Images/1A.jpg"

vb 部分截屏之后识别图片上的文字

主要是先要将图片转换为字节数组

'存放格式为(*, *, *),从左下角开始:

'第一维:0-蓝色分量,1-绿色分量,2-红色分量,

'第二维:列；第三维:行

全部步骤如下

1、用DibGet获取图片数据

2、用ColorToBlackAndWhite（或ColorToGray+OtsuColorToBlackAndWhite）将图片数据转换为黑白数据

3、用DibPut将数据恢复到一个PictureBox中

4、截取各个数字到单独的PictureBox中

5、将数字图片转换为图片数据，并与标准数据（0-9）对比，相似度最高的为准（比如与1的相似度为75%，与2的相似度为85%，则此数字为2）

有问题Hi

'图像输出的过程:

Public Sub DIBPut(ByVal IdDestination As Long, ByRef ImageData() As Byte)

Dim LineBytes As Long

Dim Width As Long, Height As Long

Width = UBound(ImageData, 2) + 1

Height = UBound(ImageData, 3) + 1

On Error GoTo ErrLine

Done = False

With bi24BitInfo.bmiHeader

.biWidth = Width

.biHeight = Height

LineBytes = ((Width * Bits + 31) And HFFFFFFE0) \ 8

.biSizeImage = LineBytes * Height

End With

SetDIBitsToDevice IdDestination, 0, 0, Width, Height, 0, 0, 0, Height, ImageData(0, 0, 0), bi24BitInfo, 0

Done = True

Exit Sub

ErrLine:

MsgBox Err.Description

End Sub

'灰度处理SrcData(0 to 2, 0 to 宽度-1, 0 to 高度-1)

Public Sub ColorToGray(ByRef SrcData() As Byte, ByRef DestData() As Byte, _

Optional Left As Long = -1, Optional Top As Long = -1, _

Optional Right As Long = -1, Optional Bottom As Long = -1)

Dim i As Long, j As Long, k As Long

Dim red As Byte, green As Byte, blue As Byte

Dim Color As Long, newcolor As Long

Dim Width As Long, Height As Long

Width = UBound(SrcData, 2) + 1

Height = UBound(SrcData, 3) + 1

If Left = -1 Then Left = 0

If Top = -1 Then Top = 0

If Right = -1 Then Right = Width - 1

If Bottom = -1 Then Bottom = Height - 1

For j = Left To Right

For k = Height - Bottom - 1 To Height - Top - 1

blue = SrcData(0, j, k)

green = SrcData(1, j, k)

red = SrcData(2, j, k)

newcolor = CLng(0.299 * CDbl(red) + 0.585 * CDbl(green) + 0.114 * CDbl(blue)) '

newcolor = newcolor * 65793

red = newcolor Mod 256

green = newcolor / 256 Mod 256 '(9798 * RValue + 19235 * GValue + 3735 * BValue) / 32768

blue = newcolor / 256 / 256

DestData(0, j, k) = blue

DestData(1, j, k) = green

DestData(2, j, k) = red

Next

Next

End Sub

'黑白处理DestData(0 to 2, 0 to 宽度-1, 0 to 高度-1)

'图片最下面两行总是无法参与变换？？？？只好将采集的图片区域向下多延伸2个像素

Public Sub ColorToBlackAndWhite(ByRef SrcData() As Byte, ByRef DestData() As Byte)

Dim i As Long, j As Long, k As Long

Dim red As Byte, green As Byte, blue As Byte

Dim Color As Long, newcolor As Long

Dim Width As Long, Height As Long

Width = UBound(SrcData, 2) + 1

Height = UBound(SrcData, 3) + 1

For j = 0 To Width - 1

For k = 0 To Height - 1

blue = SrcData(0, j, k)

green = SrcData(1, j, k)

red = SrcData(2, j, k)

newcolor = CLng(0.3 * CDbl(red) + 0.59 * CDbl(green) + 0.11 * CDbl(blue))

' newcolor = CLng(0.39 * CDbl(red) + 0.5 * CDbl(green) + 0.11 * CDbl(blue))

If newcolor 127 Then newcolor = 255 Else newcolor = 0

red = newcolor

green = newcolor

blue = newcolor

DestData(0, j, k) = blue

DestData(1, j, k) = green

DestData(2, j, k) = red

Next

Next

End Sub

'黑白处理DestData(0 to 2, 0 to 宽度-1, 0 to 高度-1)

'图片最下面两行总是无法参与变换？？？？只好将采集的图片区域向下多延伸2个像素

'OSTU算法可以说是自适应计算单阈值（用来转换灰度图像为二值图像）的简单高效方法。

'1978 OTSU年提出的最大类间方差法以其计算简单、稳定有效，一直广为使用。

Public Sub OtsuColorToBlackAndWhite(ByRef SrcData() As Byte, ByRef DestData() As Byte)

On Error Resume Next

Dim i As Long, j As Long, k As Long

Dim red As Byte, green As Byte, blue As Byte

Dim Color As Long, newcolor As Long

Dim Width As Long, Height As Long

Dim AllSum As Long, SumSmall As Long, SumBig As Long, PartSum As Long

Dim AllPixelNumber As Integer, PixelNumberSmall As Long, PixelNumberBig As Long

Dim ProbabilitySmall As Double, ProbabilityBig As Double, Probability As Double, MaxValue As Double

Dim BmpData() As Byte, Threshold As Byte

Dim Histgram(255) As Integer '图像直方图，256个点

Dim PixelNumber As Integer

Width = UBound(SrcData, 2) + 1

Height = UBound(SrcData, 3) + 1

PixelNumber = Width * Height

For i = 0 To Width - 1

For j = 0 To Height - 1

Histgram(SrcData(0, i, j)) = Histgram(SrcData(0, i, j)) + 1 '统计图像的直方图

Next

Next

For i = 0 To 255

AllSum = AllSum + i * Histgram(i) ' 质量矩

AllPixelNumber = AllPixelNumber + Histgram(i) ' 质量

Next

MaxValue = -1#

For i = 0 To 255

PixelNumberSmall = PixelNumberSmall + Histgram(i)

PixelNumberBig = AllPixelNumber - PixelNumberSmall

If PixelNumberBig = 0 Then Exit For

SumSmall = SumSmall + i * Histgram(i)

SumBig = AllSum - SumSmall

ProbabilitySmall = CDbl(SumSmall) / PixelNumberSmall

ProbabilityBig = CDbl(SumBig) / PixelNumberBig

' Probability = PixelNumberSmall * PixelNumberBig * (ProbabilityBig - ProbabilitySmall) * (ProbabilityBig - ProbabilitySmall)

Probability = PixelNumberSmall * ProbabilitySmall * ProbabilitySmall + PixelNumberBig * ProbabilityBig * ProbabilityBig

If Probability MaxValue Then

MaxValue = Probability

Threshold = i

End If

Next

For j = 0 To Width - 1

For k = 0 To Height - 1

If SrcData(0, j, k) = Threshold Then

DestData(0, j, k) = 0

DestData(1, j, k) = 0

DestData(2, j, k) = 0

Else

DestData(0, j, k) = 255

DestData(1, j, k) = 255

DestData(2, j, k) = 255

End If

Next

Next

End Sub

'迭代法 (最佳阀值法)

'(1)求出图象的最大灰度值和最小灰度值，分别记为Zl和Zk，令初始阈值为：T=(Zl+Zk)/2

'(2)根据阈值TK将图象分割为前景和背景，分别求出两者的平均灰度值Z0和ZB:

'(3)令当前阈值Tk=(Z0+ZB)/2

'(4)若TK=TK+1， 则所得即为阈值，否则转2，迭代计算。

Public Sub BestThresholdColorToBlackAndWhite(ByRef SrcData() As Byte, ByRef DestData() As Byte)

Dim i As Long, j As Long, k As Long

Dim red As Byte, green As Byte, blue As Byte

Dim Color As Long, newcolor As Long

Dim Width As Long, Height As Long

Dim PixelNumber As Integer

Dim Threshold As Integer, NewThreshold As Integer, MaxGrayValue As Integer

Dim MinGrayValue As Integer, MeanGrayValue1 As Integer, MeanGrayValue2 As Integer

Dim IP1 As Long, IP2 As Long, IS1 As Long, IS2 As Long

Dim Iteration As Long, Histgram(255) As Integer

Width = UBound(SrcData, 2) + 1

Height = UBound(SrcData, 3) + 1

PixelNumber = Width * Height

'求出图像中的最小和最大灰度值，并 计算阈值初值为

MaxGrayValue = 0: MinGrayValue = 255

For i = 0 To Width - 1

For j = 0 To Height - 1

Histgram(SrcData(0, i, j)) = Histgram(SrcData(0, i, j)) + 1 '统计图像的直方图

If MinGrayValue SrcData(0, i, j) Then MinGrayValue = SrcData(0, i, j)

If MaxGrayValue SrcData(0, i, j) Then MaxGrayValue = SrcData(0, i, j)

Next

Next

NewThreshold = (MinGrayValue + MaxGrayValue) / 2

While Threshold NewThreshold And Iteration 100

Threshold = NewThreshold

'根据阈值将图像分割成目标和背景两部分，求出两部分的平均灰度值

For i = MinGrayValue To Threshold

IP1 = IP1 + Histgram(i) * i

IS1 = IS1 + Histgram(i)

Next

MeanGrayValue1 = CByte(IP1 / IS1)

For i = Threshold + 1 To MaxGrayValue

IP2 = IP2 + Histgram(i) * i

IS2 = IS2 + Histgram(i)

Next

MeanGrayValue2 = CByte(IP2 / IS2)

'求出新的阈值：

NewThreshold = (MinGrayValue + MaxGrayValue) / 2

Iteration = Iteration + 1

Wend

For j = 0 To Width - 1

For k = 0 To Height - 1

If SrcData(0, j, k) = Threshold Then

DestData(0, j, k) = 0

DestData(1, j, k) = 0

DestData(2, j, k) = 0

Else

DestData(0, j, k) = 255

DestData(1, j, k) = 255

DestData(2, j, k) = 255

End If

Next

Next

End Sub

用vb.net实现查找显示图片？

IO.Directory.GetFiles

获取指定目录中的所有文件，比对文件名就行了。如果包括多层子目录，需要递归

VB.NET 如何获取控件上的图像的问题

你的那个图像控件叫什么？是第三方控件的话要看说明了

一般用Picture控件就可以了啊

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