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How to keep aspect ratio in panel C#?

I save an image in preview mode. Preview mode contains Picturebox and Label control.
The problem is when I save an image. Likely I recorded my screen.
The export image is different with my expect, it does not keep aspect ratio.
So, all control in panel after save to example.jpg will wrong position.
My code use to ScaleImage:
public static Image ScaleImage(Image image, int maxWidth, int maxHeight)
{
var ratioX = (double) maxWidth/image.Width;
var ratioY = (double) maxHeight/image.Height;
var ratio = Math.Min(ratioX, ratioY);
var newWidth = (int) (image.Width*ratio);
var newHeight = (int) (image.Height*ratio);
var newImage = new Bitmap(newWidth, newHeight);
Graphics.FromImage(newImage).DrawImage(image, 0, 0, newWidth, newHeight);
return newImage;
}
My code save image:
Graphics g = Graphics.FromImage(img);
string s = lstImgAdded.Items[k].Text;
Bitmap bm = new Bitmap(#"" + s);
panel2.BackgroundImage = bm;
PointF p1 = StretchImageSize(postPoint, panel2);
g.DrawImage(
DrawText(lstAliasImage[i - valuesFrom], fontType, colorInput,
Color.Transparent),
Point.Round(StretchImageSize(postPoint, panel2))); // Point.Round(StretchImageSize(postPoint, panel2)) ở đây dùng nhìu lần
g.DrawImage(ctrl.Image, Point.Round(StretchImageSize(postPointPicturebox, panel2)).X, Point.Round(StretchImageSize(postPointPicturebox, panel2)).Y,
ctrl.Width, ctrl.Height); // panel2 có phải cái hình nhỏ ko? ko. picturebox moi la nho, panel la background lon
g.Dispose();
string linkLocation = txtAddress.Text;
ScaleImage(img, witdhImg, heightImg)
.Save(linkLocation + "\\" + lstAliasImage[i - valuesFrom] + "." + imgType,
ImageFormat.Jpeg);
And class StretchImage to scale control(Picturebox, Label) with a panel.
Image show before image in a panel is different after save.
In my software, Image shown in the panel. It does not scale like in Preview software:

Applying Aspect Ratio to Windows Forms
Much like we intercepted Windows message in our Windows 7 Style Form, to keep the aspect ratio of a Windows Form we are going to intercept the resizing Windows messages. This is done by overriding WndProc.
Here is a list of the constants that we need for this algorithm:
WM_SIZING = 0x214
WMSZ_LEFT = 1
WMSZ_RIGHT = 2
WMSZ_TOP = 3
WMSZ_BOTTOM = 6
The first one is the way our C# application can tell when the Form
is being resized. The rest of the constants tell us exactly which
side of the Form is being resized. Note that for corners the edges
combine. So for example, the lower left corner would be resizing the
right and bottom parts of the form and thus be 2 + 6 = 8.
The advantage of using WndProc instead of Windows Form events is
that we can prevent the Form from flickering. Resize events in .NET
are called until after the resizing has been applied, so modifying
size in an event produces flickering.
Make sure to download the sample C# application. Notice how no
matter where you resize the Form from, the aspect ratio is
maintained. A quick peek at the source code shows how either the
height or width is adjusted depending on which side of the Form was
being resized. Another cool thing is that the Form can still be
maximized to fill the entire screen without any problems.
try this
public void ResizeImage(string OriginalFile, string NewFile, int NewWidth, int MaxHeight, bool OnlyResizeIfWider)
{
System.Drawing.Image FullsizeImage = System.Drawing.Image.FromFile(OriginalFile);
// Prevent using images internal thumbnail
FullsizeImage.RotateFlip(System.Drawing.RotateFlipType.Rotate180FlipNone);
FullsizeImage.RotateFlip(System.Drawing.RotateFlipType.Rotate180FlipNone);
if (OnlyResizeIfWider)
{
if (FullsizeImage.Width MaxHeight)
{
// Resize with height instead
NewWidth = FullsizeImage.Width * MaxHeight / FullsizeImage.Height;
NewHeight = MaxHeight;
}
System.Drawing.Image NewImage = FullsizeImage.GetThumbnailImage(NewWidth, NewHeight, null, IntPtr.Zero);
// Clear handle to original file so that we can overwrite it if necessary
FullsizeImage.Dispose();
// Save resized picture
NewImage.Save(NewFile);
}

Reduce image size in C#

I want function which will reduce image size.
The function should take the image URL, check is image 4MB size or bigger and if it is then resize it to lover then 4MB and return bytes.
I have next method:
public byte[] ResizeImage(string url)
{
var uri = new Uri(url);
var c = new WebClient();
var oldImgStream = new MemoryStream(c.DownloadData(uri));
if (oldImgStream.Length <= 4194304)
{
return oldImgStream.ToArray();
}
using (var oldImage = new Bitmap(oldImgStream))
using (var newImageStream = new MemoryStream())
{
var format = oldImage.RawFormat;
float resizePercent = (float)4194304 / oldImgStream.Length;
var newImage = ResizeImageByPercent(oldImage, resizePercent);
newImage.Save(newImageStream, format);
return newImageStream.ToArray();
}
}
public static Bitmap ResizeImageByPercent(Bitmap image, float resizePercent)
{
//Set minimum resizePercentage to 80%
resizePercent = resizePercent > 0.8 ? (float)0.8 : resizePercent;
int newWidth = (int)(image.Width * resizePercent);
int newHeight = (int)(image.Height * resizePercent);
var newImage = new Bitmap(newWidth, newHeight);
using (var graphics = Graphics.FromImage(newImage))
{
graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
graphics.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
graphics.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
graphics.FillRectangle(Brushes.Transparent, 0, 0, newWidth, newHeight);
graphics.DrawImage(image, 0, 0, newWidth, newHeight);
return newImage;
}
}
But this doesn't work fine.
I have an jpg image as example.
The image size is a little more then 4MB (4194587 bytes).
Resolution of the image is 2272 x 1704.
So when I try to resize this image with my method above.
It first calculate "resizePercentage" as:
float resizePercent = (float)4194304 / oldImgStream.Length;
resizePercent = (float)4194304 / 4194587;
resizePercent = 0.9999325 //(99.99325%)
But because I have set minimum of resizePercent it will be set to 0.8 (80%).
resizePercent = 0.8;
Then it will calculate new width and height with this resizePercent.
And new resolution will be: 1817 x 1363 and image is resized to new resolution.
But after it is saved to stream and it read bytes it returns even larger image.
Site of the returned image is "5146056 bytes" 5MB
So does anyone has idea how to implement this, or what is wrong this my method so it's returning larger image even resolution is reduced.
I should be able to reduce size of images png, jpg and gif

There's not a one to one correlation between image file size and resolution, when dealing with compressed bitmaps. That correlation does exist for a true bitmap (BMP, for example), since 1 pixel is always equal to a defined number of bytes (based on the colorspace).
However, when talking about compressed bitmaps, like JPEG, the file size is based on efficiency of the compression (how many colors needs to be encoded overall, how many pixels can combine based on being the same color, or how much dithering can be done to create more pixels of the same color that can be combined). That may end up being less with a lower resolution image, but it also could just as easily remain unchanged or even increase, depending on how efficient the original compression was and how what effect a lesser quantity of pixels overall has on the efficiency of the compression.
Long and short, you can't just apply a simple percentage-based reduction in resolution to ensure a certain file size. The best you could really to is gradually decrease the resolution, testing the file size with each iteration, until it's below your threshold, assuming it does actually go below the threshold. With 4MB to play with, there's conceivably a certain resolution that would definitely be below that, but where that point lies is virtually impossible to calculate.
Additionally, this will vary based on a the type of image format. JPEG functions mostly by trying to spread color out as much as possible (dithering). This is why lower quality JPEGs display artifacts. PNG and GIF are mostly indexed, though, where the overall amount of colors is attempted to be reduced (though both can also employ dithering as well). PNG further complicates matters in that it you can also have lossless PNGs, where all colors and pixels are preserved but a simple compression is applied (much like a ZIP archive) to reduce file size. All of these will have different behavior from each other and at various resolutions.

try to change the quality of InterpolationMode, SmoothingMode, CompositingQuality, PixelOffsetMode. You can see that all of these are set to high quality

Cropping an image to a "perfect" square like native Photos app

Whilst working on a functionality for viewing embedded images that get fetched from one of our servers, one of the requirements is to make an overview page, where all images are displayed, in a fasion like the iOS Native Photos App (square tiles, in rows of 4/5 and when tapped, displays the image screen-wide.
This has been successfully implemented, except that the images were morphed (image aspects were never taken into account). Thus, they have asked me to devise a method to crop the image, so the original aspect stays unchanged.
In order to do this, I was thinking of first resizing the image until the width reaches the max width I want it to be ((screenwidth - 10) / 4 - 5).
If the height of the image is smaller than the width, I set the height to be equal to the width, and crop the width accordingly (with aspect unchanged).
If the height of the image is greater than the width, I just want to crop the height.
This is the method I am currently using:
//Images is an array/List with base64 strings
foreach (var image in Images)
{
UIImage imageToAdd = UIImage.LoadFromData(NSData.FromArray(Convert.FromBase64String(image.Content)));
var width = imageToAdd.Size.Width;
var height = imageToAdd.Size.Height;
//GlobalSupport.ScreenWidth is a static variable that contains the actual screensize
var newWidth = (GlobalSupport.ScreenWidth - 10) / 4 - 5;
var newHeight = height * newWidth / width;
var widthToCrop = 0.0f;
var heightToCrop = 0.0f;
//If the new height is smaller than the new width, make the new height equal to the new width, and modify the new width accordingly.
if (newHeight < newWidth)
{
newHeight = newWidth;
newWidth = width * newHeight / height;
widthToCrop = newWidth - newHeight;
}
//Or, if the new height is greater than the new width, just crop the height.
else if (newHeight > newWidth)
{
heightToCrop = newHeight - newWidth;
}
UIGraphics.BeginImageContext(new SizeF(newWidth, newHeight));
var cropRectangle = new RectangleF(-widthToCrop, -heightToCrop, newWidth, newHeight);
imageToAdd.Draw(cropRectangle);
imageToAdd = UIGraphics.GetImageFromCurrentImageContext();
UIGraphics.EndImageContext();
UIButton btnToAdd = new UIButton(new RectangleF(-widthToCrop, -heightToCrop, newWidth, newHeight));
btnToAdd.SetBackgroundImage(imageToAdd, UIControlState.Normal);
btnToAdd.TouchUpInside += (sender, e) =>
{
Task.Factory.StartNew(() =>
{
//Displays a loading spinner
GlobalSupport.EnableLoadingOverlay(true, NSBundle.MainBundle.LocalizedString("txtOneMoment", "", ""));
}).ContinueWith(task => InvokeOnMainThread(() =>
{
//Navigate to the full-screen image viewer
this.NavigationController.PushViewController(
new VCDCMPhotoDetails(
UIImage.LoadFromData(
NSData.FromArray(
Convert.FromBase64String(image.Content)))), true);
GlobalSupport.EnableLoadingOverlay(false, "");
}));
};
//Add btn to the scrollable view's children
scrollView.AddSubview(btnToAdd);
}
This method works great, except for one thing: if the new height is smaller than the new width, the new height and new width successfully get modified, but after the ImageToAdd.Draw(RectangleF) the Size of the ImageToAdd still has the new width value, instead of the cropped width (that is, if I can assume that, if I draw an image with -20 as its x-value, the width gets modified with -20 as well).
I don't know if this is the right way to do it. If it isn't, then all help is welcome! If this is the right way to do it, but I'm missing something, please let me know! Thanks in advance!
When cropping the image, the x-coordinate is equal to the width of the image, minus the max width of a thumbnail: http://i.stack.imgur.com/uNm7k.png
After cropping, the image still had the original new width, instead of the cropped width: http://i.stack.imgur.com/rabeY.png
The resulting grid of images: http://i.stack.imgur.com/opo2f.jpg

Let me just show you a proper procedure on how to crop the image with a FILL operation. The code is in Swift but you should have no trouble porting it:
public static func resampleImageToSize(image: UIImage!, size: CGSize) -> UIImage {
let originalWidth = image.size.width
let originalHeight = image.size.height
let originalRatio = originalWidth/originalHeight
let targetRatio = size.width/size.height
var targetFrame = CGRect(x: 0.0, y: 0.0, width: size.width, height: size.height)
if originalRatio>targetRatio {
// crop width
let targetHeight = size.height
let targetWidth = targetHeight * originalRatio
targetFrame = CGRect(x: (size.width-targetWidth)*0.5, y: (size.height-targetHeight)*0.5, width: targetWidth, height: targetHeight)
} else if originalRatio<targetRatio {
// crop height
let targetWidth = size.width
let targetHeight = targetWidth / originalRatio
targetFrame = CGRect(x: (size.width-targetWidth)*0.5, y: (size.height-targetHeight)*0.5, width: targetWidth, height: targetHeight)
}
UIGraphicsBeginImageContext(size)
image.drawInRect(targetFrame)
let outputImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return outputImage
}
So this is a general method that takes in an original image and returns an image with a size of your choice. In your case that is the size of the icons you want to display. The operation here is fill, if you need to fit the image all you need to do is swap < and > in both if statements.

What you are doing is easiest to achieve with creating an image view with the size of your target image size. Then set your image to it and set the content mode to scale aspect fill and simply create a screenshot of the view (you can find very easy solutions for that on the web).
From your question I can not see if you have an issue at all or what it is. But one thing is bothering me. The line
RectangleF(-widthToCrop, -heightToCrop, newWidth, newHeight)
Will crop it the way you will always get the bottom right part of the image. You should most likely center it:
RectangleF(-widthToCrop*0.5, -heightToCrop*0.5, newWidth, newHeight)
Ok I think I found your problem. The frame you compute is the frame on which you should draw the image to put it on the square. But when you begin image context you should set the size to be a square. So if the width is larger the size should be (newHeight, newHeight) otherwise (newWidth, newWidth). The button frame makes no sense to me either. Why are you using the rectangle that should be used only to redraw the image?

Adding a frame to an Image (Bitmap) and Saving it - Error in Border

I am trying to open an image, add a border to it and save the image in C#.
I got a code, I guess it was an answer from stack overflow. Here it is:
public Bitmap AddBorder(Bitmap image, Color color, int size)
{
Bitmap result = new Bitmap(image.Width + size * 2, image.Height + size * 2);
Graphics g = Graphics.FromImage(result);
g.Clear(color);
int x = (result.Width - image.Width) / 2;
int y = (result.Height - image.Height) / 2;
g.DrawImage(image, new Point(x, y));
g.Dispose();
return result;
}
I save the image using:resultimage.save(fileName);
I tested it with an image 5MP in size. And saved the image to the disk. But there is an error.
The result has a border in left side of it and on top of it. The image seems to be zoomed. For example the saved image would miss parts of it (from right size and bottom).
Am I doing any thing wrong?
Thanks in advance.

This will go wrong as described when the resolution of the input bitmap doesn't match the resolution of your video adapter. Something you can see with the debugger. Add watches for image.HorizontalResolution and result.HorizontalResolution. You'd only get a match by accident. DrawImage(Image, Point) will rescale the image to make the resolutions match so that the apparent size of the image is the same as on the machine on which the bitmap was designed.
You solve it by using the Graphics.DrawImage(Image, Rectangle) overload so you directly control the final size of the image. Fix:
g.DrawImage(image, new Rectangle(x, y, image.Width, image.Height));

How do you square an uploaded photo without padding with white space, in C#?

In my site, users can upload photos. I currently compress and resize the photo to make sure they aren't huge files. But this creates photos that are of varying dimensions... which makes the site a bit "ugly" in my opinion.
I'd like to ensure the thumbnails are square images, but not by using padding. It's ok if there is some loss of the photo in the thumbnail. I'd like to keep the fidelity of the photo high, even if it means some cropping needs to occur.

I wrote some code to do this exact thing. I chose to crop it because resizing without preserving aspect ratio looks pretty horrible. I do a crop then a resize to create a thumnail image:
public Bitmap CreateThumbnail(Bitmap RawImage)
{
int width = RawImage.Width;
int height = RawImage.Height;
Size ThumbnailDimensions = new Size();
ThumbnailDimensions.Width = 100;
ThumbnailDimensions.Height = 100;
Rectangle cropArea = new Rectangle();
if (width > height)
{
cropArea.Width = height;
cropArea.Height = height;
cropArea.X = 0;
cropArea.Y = 0;
}
else if (width < height)
{
cropArea.Width = width;
cropArea.Height = width;
cropArea.X = 0;
cropArea.Y = 0;
}
if(width != height) Bitmap thumbnail = CropImage(RawImage, cropArea);
thumbnail = ResizeImage(thumbnail, ThumbnailDimensions);
return thumbnail;
}
This just crops from the top left corner then resizes it to my thumbnail dimensions.

I would imagine you need to take the shortest dimension (either w or h), and use that as your dimension for creating the cropped image, essentially you can crop and then scale the image. Check out this article as an example for cropping an image. Also check out this Stack Overflow question regarding image quality.

Rather than cropping, I would make the div or whatever you put them in a fixed square size. Scale the image to fit inside that square.
How would you decide to crop it? From the top-left? Bottom-right? Center?

To make a rectangle into a square you need to either pad, resize without preserving aspect ratio or crop (or combinations).
Here's some code for cropping
http://snippets.dzone.com/posts/show/1484
(I work for Atalasoft -- in our DotImage Photo SDK), it's
AtalaImage img = new AtalaImage("filename.jpg");
AtalaImage img2 = new CropCommand( /*point and size of crop */).Apply(img).Image;
img2.Save("filename", new JpegEncoder(quality), null);