Get info on my source  png file.  file  old.png old.png: PNG image data, 600 x 800, 8-bit colormap, non-interlaced   I want to convert old.png from 600 x 800  into  600 x 400.  convert -resize 600x400  old.png  new.png   Check my output.  file new.png new.png: PNG image data, 300 x 400, 8-bit/color RGB, non-interlaced
120437
I'm batch processing a folder of image to a uniform width with GraphicsMagick (though I assume the same would apply to ImageMagick):  $ gm convert -resize 1000x in.jpg out.jpg   But when I inspect some of the images, I get 999px instead of 1000px.  $ gm identify -verbose out.jpg  ==&gt; Image: out.jpg ==&gt; Format: JPEG (Joint Photographic Experts Group JFIF format ==&gt;   Geometry: 999x591   Is there a way to enforce the right width? I assume it's doing some estimation to preserve aspect ratios.
1544
(This question is meant to be a resource to direct others to given that this is a common question.)  Given the task of creating an image that will be printed at a certain size, what pixel dimensions and resolution should I be setting my file at?
31697
I just selected some pixels in Photoshop and deleted them, so this part became transparent. I save it as PNG. And imported this image as texture for cycles material.  What surprised me is a "Material" and "Texture" view in 3D window, that displays pixels that should not exist anymore in the image.  From result it seems to me like Ph deleted completely only all pixels (color information) out of a box (rectangle) that determinate pixels with alpha. And for pixels inside this "non alpha" box he kept colors and alpha info.  Blender than displays only color info without alpha inside this rectangle. That is probably a bug, but I just even didn't know that PNG saves this pixels as well.   Am'I right? Or what is going on here?  Since the node tree consists from a "Transparent" shader as well, it displays alpha right, but not in a "Texture" method anyway.   Note: Render is OK.  So, the questions are:   How PNG file stores color/transparent data (this doesn't seem to be blender related, but only blender displays data in that way for me) Is this behaviour expected or is it a bug? (or any other user fault :)     Edit: probably more descriptive illustration
109234
I am attempting to fully automate the process of georeferencing a load of .png files - i have xml file containing the co-ordinates - but how can i use them?  Does anyone have any advice?
122579
I cannot get ArcMap 10.0 or 10.1 to "Export Map" to a png or gif with a transparent background -- no matter what I set the background and transparent colors to.  Thus, I created the following script, which does the trick, but I'd rather be able to get the default tool in ArcMap to do it.  Any better ideas?    # Purpose: This script exports an MXD view to a png file with transparent background, # which is problematic to do manually due to a Windows-related bug in the ArcMap UI. # Warning: It will make any white features (e.g. the default background color) transparent. # # INSTRUCTIONS: # When in ArcMap, viewing a saved mxd... # 1. From the Geoprocessing menu, select 'Python'. # 2. In the new Python window, right-click somewhere after &gt;&gt;&gt;, and select 'Load...' # 3. Select this script. # 4. When this script appears, press Enter twice to run it. # 5. A new [mxd-name].png with transparent background will appear in the same directory as the mxd. # 6. When finished/satisfied, close the Python window. # http://forums.arcgis.com/threads/65463-Zoom-to-tile-and-Export-to-JPEG-with-World-File import arcpy png_resolution = 300    # Can adjust DPI # Set mxd and png name mxd = arcpy.mapping.MapDocument("CURRENT") pngname = mxd.filePath.replace(".mxd",".png") df = arcpy.mapping.ListDataFrames(mxd)[0] # Calculate ideal image size from the mxd view and desired DPI png_width = int((df.extent.XMax - df.extent.XMin) * png_res * 12 / df.scale) png_height = int((df.extent.YMax - df.extent.YMin) * png_res * 12 / df.scale) #Export PNG print "Exporting: {0}\n{1} x {2} pixels, {3}-dpi".format(pngname,png_width,png_height,png_res) arcpy.mapping.ExportToPNG(mxd, pngname, df, df_export_width = png_width, df_export_height = png_height, resolution = png_res, transparent_color = "255, 255, 255") #Clean up del df, pngname, png_res, png_width, png_height, mxd
62187
I was experimenting with JPEG quality loss upon resaving and noticed that not only (even after four resaves) did the quality not degrade (down to pixel level), but the file sizes actually increased by 200 kb or so each time.  Can anyone give an explanation for this?  Where is this newly created information that increases the file size even coming from?  I would have expected at least slight degradation and a decrease in file size. I saved using Photoshop’s save for web function and 100 % quality.      *Original (top) - 798kb *After 5 saves (bottom) - 1020kb
58216
I just made a video in mov-formate containing 300pngs in 4k. Every single png ist roughly 6MB in filesize. The mov-file is just 8MB. Seems weird to me. Is there maybe a quality loss in the video? The video looks fine but the size just seems so small.
19568
I made a huge project, wanted to reduce file size from 1.3GB to below 1GB. Compressing did not help. I removed objects from scene. Also textures. I then realized, the file size even was the same when I delete ALL objects. Why?  Download of sample:   Before deleting all: 1.2GB, after: 1.1GB.
38371
I'm attempting to resize pngs with transparent backgrounds in PHP and the code samples I've found online don't work for me. Here's the code I'm using, advice will be much appreciated!  $this-&gt;image = imagecreatefrompng($filename);  imagesavealpha($this-&gt;image, true); $newImage = imagecreatetruecolor($width, $height);  // Make a new transparent image and turn off alpha blending to keep the alpha channel $background = imagecolorallocatealpha($newImage, 255, 255, 255, 127); imagecolortransparent($newImage, $background); imagealphablending($newImage, false); imagesavealpha($newImage, true);  imagecopyresampled($newImage, $this-&gt;image, 0, 0, 0, 0, $width, $height,  $this-&gt;getWidth(), $this-&gt;getHeight()); $this-&gt;image = $newImage;   imagepng($this-&gt;image,$filename);    Update By 'not working' I meant to say the background color changes to black when I resize pngs.
10100
I have a photo with a resolution of $1024 \times 768$ which means $786432$ pixels in total. Let's suppose it's a 24-bit color RGB image (so 1 pixel = 3 bytes = 24 bits) and I want to hide information by only modifying the last bit of a color value. What is the maximum number of bytes that I can hide in this photo?
81794
I need to resize PNG, JPEG and GIF files. How can I do this using Java?
68042
I've made some high resolution pixel art in PS by drawing it down at the pixel level and then increasing the image size with the nearest neighbor setting to keep it crisp. In the web browser, however, I need to display these images as icons with a dynamic size, so I can't just size the images correctly to begin with, and the broswer seems to blur the images when rendering them smaller, while vector images seem to stay more crisp as they shrink.   So I'm wondering if there's a way to convert the pixel art neatly into vector. I'm aware of the trace function in illustrator, but it seems to do a rough job iirc.
31471
How do I get a human-readable file size in bytes abbreviation using .NET?  Example: Take input 7,326,629 and display 6.98 MB
84763
I have two image tabs open and I want to copy one layer from the first image to  the second image keeping dimensions and size.  How would I do that?  Example:  I have this 640px by 400px first image with two layers - the background and a brush    and I want to copy the brush layer to this other image of 1600px by 1200px.
68658
I have a 72.9MB PDF file that I need to shrink into under 500KB.  The file was a JPEG image that I had scanned, and then converted to pdf.
33176
I am submitting a photo for an exhibit.  They require a jpeg to be evaluated and then a print, if accepted.  The rules indicate "Entries must be in JPEG format sized at 300 dpi on a CD (4” width of image 1,200 pixels at 300 dpi is the largest dimension please)." The final submission will be a maximum of 36" x 36".  I don't see any of this in the photo's properties.  What exactly are they looking for?
91443
What does the output mean when you do cat image.png?  Is this what the image actually is made of?  Does it matter what file extension the image has?