I want to resize an image into a 4x4 pixel image in vb.net.
Using the Internet I got this code:
Public Function ResizeImage(ByVal image As Image) As Image
Try
Dim newWidth = 4
Dim newHeight = 4
Dim newImage As New Bitmap(newWidth, newHeight)
newImage.SetResolution(100, 100)
Using graphicsHandle As Graphics = Graphics.FromImage(newImage)
graphicsHandle.InterpolationMode = InterpolationMode.HighQualityBicubic
graphicsHandle.DrawImage(image, 0, 0, newWidth, newHeight)
End Using
Return newImage
Catch ex As Exception
Return image
End Try
End Function
Original:
Resized with photoshop(the real way of resizing it):
using InterpolationMode.Bilinear
using InterpolationMode.HighQualityBicubic
What is the problem ?
The settings you'll want are bilinear or bicubic interpolation (avoid the "high-quality" options) and PixelOffsetMode.Half.
graphicsHandle.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.Bilinear
graphicsHandle.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.Half
When interpolating, GDI+ normally offsets the center of the pixel by a half pixel. This can have an undesirable effect when scaling, with the appearance of shifting the scaled image up and left. Using PixelOffsetMode.Half shifts the pixels back where they "belong".
The high-quality bilinear and bicubic interpolation modes appear to blend the edge pixels with hypothetical transparent pixels beyond the image bounds, creating a fringe of semi-transparency at the edges.
Related
Curently based on Sascha Willems examples I've cerated samplerCube texture for fragment shader.
It has same JPG image copied to all 6 layers (faces).
I use stbi image library for image loading, it works okay if I use it for regular 2D texture, but if it's mapped on cube mesh it creates distorted image:
int width = 0, height = 0, channel = 0;
float* pixels = stbi_loadf("textures/test.hdr", &width, &height, &channel, STBI_rgb_alpha);
if(!pixels) throw std::runtime_error("failed to load texture image!");
this->texture_image.create_image(width, height, VK_FORMAT_R32G32B32A32_SFLOAT, VK_IMAGE_USAGE_TRANSFER_DST_BIT | VK_IMAGE_USAGE_SAMPLED_BIT);
this->texture_image.fill_memory(width, height, 4*sizeof(float), pixels);
this->texture_image.create_image_view(VK_FORMAT_R32G32B32A32_SFLOAT, VK_IMAGE_ASPECT_COLOR_BIT);
stbi_image_free(pixels);
Found how to do it here: https://learnopengl.com/PBR/IBL/Diffuse-irradiance
Even if it's in OpenGL the concenpt is the same.
I have an app written with RXSwift which processes 500+ days of HealthKit data to draw a chart for the user.
The chart image is drawn incrementally using the code below. Starting with a black screen, previous image is drawn in the graphics context, then a new segment is drawn over this image with certain offset. The combined image is saved and the process repeats around 70+ times. Each time the image is saved, so the user sees the update. The result is a single chart image which the user can export from the app.
Even with autorelease pool, I see spikes of memory usage up to 1Gb, which prevents me from doing other resource intensive processing.
How can I optimize incremental drawing of very large (1440 × 5000 pixels) image?
When image is displayed or saved at 3x scale, it is actually 4320 × 15360.
Is there a better way than trying to draw over an image?
autoreleasepool {
//activeEnergyCanvas is custom data processing class
let newActiveEnergySegment = activeEnergyCanvas.draw(in: CGRect(x: 0, y: 0, width: 1440, height: days * 10), with: energyPalette)
let size = CGSize(width: 1440, height: height)
UIGraphicsBeginImageContextWithOptions(size, false, 0.0)
//draw existing image
self.activeEnergyImage.draw(in: CGRect(origin: CGPoint(x: 0, y: 0),
size: size))
//calculate where to draw smaller image over larger one
let offsetRect = CGRect(origin: CGPoint(x: 0, y: offset * 10),
size: newActiveEnergySegment.size)
newActiveEnergySegment.draw(in: offsetRect)
//get the combined image
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
//assign combined image to be displayed
if let unwrappedImage = newImage {
self.activeEnergyImage = unwrappedImage
}
}
Turns out my mistake was in passing invalid drawing scale (0.0) when creating graphics context, which defaulted to drawing at the device's native screen scale.
In case of iPhone 8 it was 3.0 The result is needing extreme amounts of memory to draw, zoom and export these images. Even if all debug logging prints that image is 1440 pixels wide, the actual canvas ends up being 1440 * 3.0 = 4320.
Passing 1.0 as the drawing scale makes the image more fuzzy, but reduces memory usage to less than 200mb.
// UIGraphicsBeginImageContext() <- also uses #3x scale, even when all display size printouts show
let drawingScale: CGFloat = 1.0
UIGraphicsBeginImageContextWithOptions(size, true, drawingScale)
I have a grayscale image that serves as a soft mask and I want to use it on a group of PDF objects (images or paths).
The mask and the objects do not necessarily use the same transformation matrix, and there might be more than one object to mask, so that excludes the possibility of using the SMask attribute of the ImageXObject dictionary.
So after reading some of the PDF specification, it looks like I should do the following: create a transparency group with the objects to mask, then draw it with the soft mask set on the graphics state.
Will that work? How can I achieve this, preferably with PDFBox?
Here's an example. I have these two images: the mask and another image.
The mask image is 200x200. It is drawn with the matrix [[4 0 100] [0 4 100]].
The image is 400x300. It is drawn with the matrix [[2 0 100] [0 2 150]].
Additionally, a 400x400 black square is drawn below the image with no transform matrix.
So a transparency group is created with the image and the square, then it's drawn with the mask image. Here's the expected result:
Rather ugly as far as the effect goes, but that's just an example.
As far as I can see establishing an extended graphics state soft mask is a very manual task in PDFBox. You can do so as follows:
try ( PDDocument document = new PDDocument() ) {
final PDImageXObject image = RETRIEVE PHOTO IMAGE;
final PDImageXObject mask = RETRIEVE MASK IMAGE;
PDTransparencyGroupAttributes transparencyGroupAttributes = new PDTransparencyGroupAttributes();
transparencyGroupAttributes.getCOSObject().setItem(COSName.CS, COSName.DEVICEGRAY);
PDTransparencyGroup transparencyGroup = new PDTransparencyGroup(document);
transparencyGroup.setBBox(PDRectangle.A4);
transparencyGroup.setResources(new PDResources());
transparencyGroup.getCOSObject().setItem(COSName.GROUP, transparencyGroupAttributes);
try ( PDFormContentStream canvas = new PDFormContentStream(transparencyGroup) ) {
canvas.drawImage(mask, new Matrix(400, 0, 0, 400, 100, 100));
}
COSDictionary softMaskDictionary = new COSDictionary();
softMaskDictionary.setItem(COSName.S, COSName.LUMINOSITY);
softMaskDictionary.setItem(COSName.G, transparencyGroup);
PDExtendedGraphicsState extendedGraphicsState = new PDExtendedGraphicsState();
extendedGraphicsState.getCOSObject().setItem(COSName.SMASK, softMaskDictionary);
PDPage page = new PDPage(PDRectangle.A4);
document.addPage(page);
try ( PDPageContentStream canvas = new PDPageContentStream(document, page) ) {
canvas.saveGraphicsState();
canvas.setGraphicsStateParameters(extendedGraphicsState);
canvas.setNonStrokingColor(Color.BLACK);
canvas.addRect(100, 100, 400, 400);
canvas.fill();
canvas.drawImage(image, new Matrix(400, 0, 0, 300, 100, 150));
canvas.restoreGraphicsState();
}
document.save(new File(RESULT_FOLDER, "SoftMaskedImageAndRectangle.pdf"));
}
The result:
If I were you, though, I would not use a bitmap image for the soft mask but instead a PDF gradient. The result most likely will be much less pixelated.
How do you fade out/in a button in VB.NET properly? I can fadeout/in labels using:
Controls(i).ForeColor = Color.FromArgb(255, alpha, alpha, alpha)
(where Controls(i) is a label from a For Next loop through all controls in Me.Controls; alpha is the value of the RGB, also from a For Next loop).
This did not work for me with buttons because changing the ForeColor leaves the rest of the buttons' UIs visible!
So, the way I'm trying uses a saved Resource image of the button (from a screenshot) and creates a faded in/out version to be displayed as the image in a PictureBox:
Public Function SetImageOpacity(ByVal imgPic As Image, ByVal imgOpac As Double) As Image
Dim bmpPic As New Bitmap(imgPic.Width, imgPic.Height)
Dim grPic As Graphics = Graphics.FromImage(bmpPic)
Dim imgAtt As New ImageAttributes()
Dim cmxPic As New ColorMatrix()
cmxPic.Matrix33 = imgOpac
imgAtt.SetColorMatrix(cmxPic, ColorMatrixFlag.[Default], ColorAdjustType.Bitmap)
grPic.DrawImage(imgPic, New Rectangle(178, 144, bmpPic.Width, bmpPic.Height), imgPic.Width, imgPic.Height, imgPic.Width, imgPic.Height, GraphicsUnit.Pixel, imgAtt)
grPic.Dispose()
imgAtt.Dispose()
Return bmpPic
End Function
(where imgPic is the Resource image of the button, and imgOpac is the opacity on a scale of 1 to 0, where 0 is transparent).
I then use this image to set my PictureBox's image:
picbox.Image = SetImageOpacity(My.Resources.Nextbutton, 1)
However, I get a glitch where, even though the PictureBox is located at coordinates 178, 144, the image it is showing is displayed at the left edge of the form (i.e. wrong X coordinate), with the Y coordinate correct!
I have a feeling it may lie with my call of .DrawImage(...) (at line 8 of the function) - but the MSDN docs on this subject are very unclear to me.
Please link if this has been asked before!
The coordinates in the Graphics grPic are client coords relative to the image itself, not the Form. So (0, 0) is the top left of the image regardless of where that image ends up being displayed in some kind of control.
Try changing it to (0, 0):
grPic.DrawImage(imgPic, New Rectangle(0, 0, bmpPic.Width, bmpPic.Height), imgPic.Width, imgPic.Height, imgPic.Width, imgPic.Height, GraphicsUnit.Pixel, imgAtt)
why not just use a for loop to change the opacity of the button control from 1 to 0 in increments of say .01 ?
I am trying to learn how to do OpenGL using OpenTK and I can successfully draw polygons, circles, and triangles so far but my next question is how to draw text? I have looked at the example on their homepage which was in C# and I translated it to VB .NET.
It currently just draws a white rectangle so I was hoping that someone could spot an error in my code or suggest another way to draw text. I will just list my paint event.
Paint event:
GL.Clear(ClearBufferMask.ColorBufferBit)
GL.Clear(ClearBufferMask.DepthBufferBit)
Dim text_bmp As Bitmap
Dim text_texture As Integer
text_bmp = New Bitmap(ClientSize.Width, ClientSize.Height)
text_texture = GL.GenTexture()
GL.BindTexture(TextureTarget.Texture2D, text_texture)
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, All.Linear)
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, All.Linear)
GL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Rgba, text_bmp.Width, text_bmp.Height, 0 _
, PixelFormat.Bgra, PixelType.UnsignedByte, IntPtr.Zero)
Dim gfx As Graphics
gfx = Graphics.FromImage(text_bmp)
gfx.DrawString("TEST", Me.Font, Brushes.Red, 0, 0)
Dim data As Imaging.BitmapData
data = text_bmp.LockBits(New Rectangle(0, 0, text_bmp.Width, text_bmp.Height), Imaging.ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format32bppArgb)
GL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Rgba, Width, Height, 0, PixelFormat.Bgra, PixelType.UnsignedByte, data.Scan0)
text_bmp.UnlockBits(data)
GL.MatrixMode(MatrixMode.Projection)
GL.LoadIdentity()
GL.Ortho(0, width, Height, 0, -1, 1)
GL.Enable(EnableCap.Texture2D)
GL.Enable(EnableCap.Blend)
GL.BlendFunc(BlendingFactorSrc.One, BlendingFactorDest.OneMinusSrcAlpha)
GL.Begin(BeginMode.Quads)
GL.TexCoord2(0.0F, 1.0F)
GL.Vertex2(0.0F, 0.0F)
GL.TexCoord2(1.0F, 1.0F)
GL.Vertex2(1.0F, 0.0F)
GL.TexCoord2(1.0F, 0.0F)
GL.Vertex2(1.0F, 1.0F)
GL.TexCoord2(0.0F, 0.0F)
GL.Vertex2(0.0F, 1.0F)
GL.End()
GlControl1.SwapBuffers()
You'll get a white rectangle if your card doesn't support NPOT (non-power-of-two) texture sizes. Try testing by setting the bitmap size to e.g. 256x256.
That is an ok method. If you plan to draw lots of text or even a medium amount, that will absolutely destroy performance. What you want to do is look into a program called BMFont:
www.angelcode.com/products/bmfont/
What this does is create a texture atlas of text, along with an xml file with the positions, width and height and offsets of every letter. You start off by reading that xml file, and loading each character into a class, with the various values. Then you simply make a function that you pass a string which binds the atlas, than depending on the letters in the string, draws a quad with texture coordinates that vary on the xml data. So you might make a:
for each _char in string
create quad according to xml size
assign texture coordinates relative to xml position
increase position so letters don't draw on top of each other
There are tutorials in other languages on the BMFont website which can be helpful.