i have to convert 60px X 60px images to png for my web site with imagemagick.
convert image.jpg image.png
But it's return an image with 4kbyte size.
I want get a size around 1kbyte.
How can i do?
thanks
Compression level is controlled by the -quality parameter, look here for more information. If you are only having images with less than 256 colors, use -format PNG8 to save some bytes. And try to add -type optimize.
Related
I'd like to batch convert .heic images (e.g. iPhone photograph) to .jpg files with imagemagick, with the goal of retaining as much of the quality from the original image as possible. To be clear, the resulting output size is not a concern.
I've been using
magick input.heic -quality 100% output.jpg
Is it possible to do better?
No, its not possible to do better per ImageMagick's website:
Set the quality to 100 to produce lossless HEIC images. Requires the libheif delegate library.
I interpret lossless as NOTHING is lost from original picture. However since you ARE converting to another file type maybe its possible you lose something, are you seeing any artifacts/issues?
I need to convert PNG to JPEG,JPEG 2000 using ImageMagick and Matlab. I want to compress all data with ratio ( e.g. 10) and then specify some file size? Any idea or solution to achieve the specific file size? How can I do it? Thanks
Imagemagick can create a JPG of your desired file size. See http://www.imagemagick.org/Usage/formats/#jpg
-define jpeg:extent={size}
As of IM v6.5.8-2 you can specify a maximum output filesize for the JPEG image. The size is specified with a suffix. For example "400kb".
Unable to convert a JPEG image into a 300 DPI PNG image using ImageMagick.
After conversion the PNG image is 72 DPI only. I'm using ImageMagick 6.9.0-0 Q16 x86 and Ghostscript v9.15.
Below is the line I use in my Perl script:
system("\"$imagemagick\" -set units PixelsPerInch -density 300 \"$jpg\" \"$png\"");
Adjusting the units & density will not alter the underlining image data, but updates meta info for rendering libraries. Important for vector to raster, but not very useful for raster to raster. To adjust the DPI of an image, use the -resample operation.
convert source.jpg -resample 300 out.png
You verify the DPI resolution with the following...
identify -format "%[resolution.x] %[resolution.y]\n" out.png
I'm wondering where the 72dpi is coming from. Assuming you are using X and some kind of Unix, ImageMagick defaults to using the screen resolution (72 dpi). I'm not sure what it does under OSX/XQuartz but it's likely similar. Is your screen resolution set to 72dpi (!?).
I'm with #emcconville #ikegami - just do this straight from ImageMagick on the commandline - passing the right options to be sure.
There are image manipulation modules that you can use from perl without having to resort to system commands as well such as Imager::Transformations, Image::Magick, and GD. Here's how to convert with GD.
perl -MGD -E 'my $imgjpg = GD::Image->newFromJpeg("img.jpg");
open my $imgpng, ">", "img.png" or die; print $imgpng $imgjpg->png();'
With most image manipulation packages the original resolution show be maintained during conversion - though some (including GD) will default to lower color depths (8 bit) unless passed a Truecolor flag.
e.g. GD::Image->newFromJpeg("img.jpg", 1);
Is there anyway to reduce the Image file size or Raw RGB buffer ?
Actually I have RGB buffer which it has 500KB with 320X420 size.I tried to save it to disk using UIimage and it comes to 240 KB.
As per the image size, I want it to have less than 50KB or so.(loosing quality is OK)
Is it possible ?
Thanks,
Raghu
See Trevor Harmon's excellent post on the subject.
The 240KB size sounds exactly like the raw RGB image data, uncompressed (320x420x3). Doesn't the iPhone have a PNG or JPEG exporter? The internet says to use UIImageJPEGRepresentation or UIImagePNGRepresentation and NSData writeToFile.
I am converting eps (Encapsulated PostScript) files to jpeg files with ghostscript. A sample command I use is:
gswin32.exe -sDEVICE=jpeg -dJPEGQ=100 -dNOPAUSE -dBATCH -dSAFER -r600x600 -dGraphicsAlphaBits=4 -dUseCIEColor -dEPSCrop -sOutputFile=”a.jpeg” b.eps
The input eps files come with white backgrounds (I only have their clipping path). What I need to do is change this white background to another color in the output images, or it would be even better if I could make them transparent (output file format would be png). How can I do this?
never tried it myself but you should be able to convert your eps file into png by setting:
-sDEVICE=pngalpha
also the pngalpha device has a -dBackgroundColor option:
-dBackgroundColor=16#RRGGBB (RGB color, default white = 16#ffffff) For
the pngalpha device only, set the
suggested background color in the PNG
bKGD chunk. When a program reading a
PNG file does not support alpha
transparency, the PNG library converts
the image using either a background
color if supplied by the program or
the bKGD chunk. One common web browser
has this problem, so when using on a web page you
would need to use
-dBackgroundColor=16#CCCC00 when creating alpha transparent PNG images
for use on the page.
more details here: Details of Ghostscript output devices see section 3.1. PNG file format
After you've obtained your (white background) images from Ghostscript, you could use ImageMagick's convert or GraphicMagick's gm convert commands to change the white to transparent background:
convert -background transparent my.png my_transp.png