How can I compose (adjoin) multiple JPEG files without re-compression?
I know there is jpegtran that can losslessly crop and resize JPEG images, so I wonder if there is similar tool to adjoin images lossless?
Their size is a multiple 1 MCU block (16 pixels in both directions).
Newer versions of jpegtran include lossless "crop 'n' drop" (or "cut & paste") features. Via the command line, you can use -crop to create a larger image based on one of the pieces, and -drop to paste subsequent images into the combined image. Unfortunately, multiple -drop options aren't currently supported, so jpegtran needs to be invoked once for every part.
jpegtran -outfile combined.jpg -copy all -crop ${totalWidth}x${totalHeight} part-0.jpg
jpegtran -outfile combined-tmp.jpg -copy all -drop +${xOff[1]}+${yOff[1]} part-1.jpg combined.jpg && mv combined-tmp.jpg combined.jpg
...
jpegtran -outfile combined-tmp.jpg -copy all -drop +${xOff[$n]}+${yOff[$n]} part-$n.jpg combined.jpg && mv combined-tmp.jpg combined.jpg
Your mileage may vary depending on the exact properties of the image parts.
What you want to do is certainly possible, but in order for it to be truly lossless, both images must use the same quantization tables and color subsampling option. If, for example, the 2 images come from the same source (e.g. camera), then you can be pretty sure that it would be possible. You would need to entropy-decode each MCU in both images, rearrange them the way you want and then re-entropy code them and output the JPEG bitstream. If you want to overlay one on the other or crop/merge them on non-MCU boundaries, then you hit the same problem as above and must do a full decode and re-encode.
I've used ImageMagick's composite binary to watermark a JPG with a PNG image.
Like this:
composite -tile -dissolve 15 targetimage.jpg watermark.png
You can obviously use two JPEGs to achieve what you're looking for.
Using the -quality and -sampling-factor arguments will help retain quality. There is also a -compress <type> argument, where type can by Lossless. However, ImageMagick does not recommend the use of this value as the JPEG library must be patched to support this.
It's worth investigating though if it will achieve a genuine lossless image, and you're not happy with the quality of the compress and sampling-factor arguments.
Related
I have recently learned how to read ppm3(P3) images in C++. I just read RGB pixels written in a plain format. I want to convert some certain jpg pictures to ppm3 and then experiment with different things, like identifying numbers there, the circled answers in exam papers, etc.
I have tried this website: https://convertio.co/pdf-ppm/, but it transformed a photo in the P6 format. Could anyone help?
You can use ImageMagick in the Terminal/shell:
magick INPUT.JPG -compress none OUTPUT.PPM
If you omit -compress none you'll get binary (i.e. P6) PPM output.
If using old v6 ImageMagick, that becomes:
convert INPUT.JPG -compress none OUTPUT.PPM
All the options, switches, operators and settings for ImageMagick are documented here.
If you want to convert PPM to JPEG, or to PNG, you can just use:
magick INPUT.PPM OUTPUT.JPG
or
magick INPUT.PPM OUTPUT.PNG
You can also programmatically create a random PPM file like this:
#!/bin/bash
W=5; H=4
echo "P3\n${W} ${H}\n255" > image.ppm
for ((i=0;i<$((W*H*3));i++)) ; do
echo $((RANDOM%255))
done >> image.ppm
Then enlarge for easy viewing and make into a PNG:
magick image.ppm -scale 200x result.png
Or, the same thing again, nut maybe slightly more elegantly and without creating an intermediate file:
#!/bin/bash
W=5; H=4
{
printf "P3\n${W} ${H}\n255\n"
for ((i=0;i<$((W*H*3));i++)) ; do
echo $((RANDOM%255))
done
} | magick ppm:- -scale 200x result.png
If you prefer to use the lighter weight, but far less capable NetPBM tools, it would be:
jpegtopnm -plain INPUT.JPG > OUTPUT.PPM
For parsing pixels P6 is probably more useful for binary apps like C
P3 is about 4 times bigger than P6
both P3 and P6 are uncompressed format 1 entry = one pixel component
normally 3 components = 1 pixel (rgb) here is a white cow in a snowfield
each 255 on the Ascii =ÿ in the binary thus faster to count one byte text ÿ than 4 byte 255 the main advantage for P3 is when using an ascii editor to fettle the values as number key inputs (modify lower order numbers as 000 - 031 control code values becomes a problem in text editors)
SAFE binary bytes were used for Ansi Art as here this is a binary.ppm (just using safe non control codes.
The binary version (P6 uncompressed) is most easily generated For PDF users by xpdf or poppler pdftoppm (one single executable no real need for more than that).
http://www.xpdfreader.com/download.html
For Jpeg you can use jpegtopnm as described in other answer by Mark
https://sourceforge.net/projects/netpbm/files/
for docs and other info see https://netpbm.sourceforge.net/doc/
for binaries on windows the Cygwin / GNUwin32 ports may be useful but older 2005 https://gnuwin32.sourceforge.net/packages/netpbm.htm One exe & 4 dlls
for better description see https://en.wikipedia.org/wiki/Netpbm#File_formats
for windows related viewing see https://github.com/vbaderks/netpbm-wic-codec and also possibly conversion https://github.com/peirick/ZackViewer
I've got a 16x512 image comprised of 16x16 images. I want to seperate them, individually scale each one down to 16x8, then put them all back into their full 16x512. I've got a basic idea, but I'm having trouble executing it.
Using the commands from unix stackexchange, I split by file by using convert -crop 16x16 my_image.png crop-%d.png, which yields 32 images (512 / 16 == 32). My next step was where trouble has started. From askubuntu, I found the command mogrify -resize 16x8 crop-*.png, however this does not yield 16x8 images, but rather 8x8, which I do not want. Furthermore, this post on stackoverflow gives me the command for merging these images, which is convert crop-*.png -append my_image_cropped.png, however it does not yield a 16x512 like I want, but rather 8x256 (the 8 is due to the previous bug, but I still want a height of 512, not 256).
What do I need to accomplish my goals? The image in question can be found on imgur.
Edit: Here are some images which will describe the basic idea
The full image:
Both 16x16 and 16x8 side by side
The finalized image, basically the 16x8 will sit in the 16x16 area (right at the bottom part, that is essential), but won't fully fill it.
I am not sure I understand what you want to do. But if you resize 16x8, Imagemagick will keep aspect ratio. If you want to force it to be exactly 16x8 and can accept distortion, then use the ! flag. But you then say you want to put the 32 pieces back to form 16x512, but the resize will make it 16x256, since you have 32 image of height 8. So you have to resize again. Here is how to do that, if that is really what you want.
Create a gradient image for testing:
convert -size 16x512 gradient: grad.png
Do the processing:
convert grad.png -crop 16x16 -resize 16x8! -append -resize 16x512! newgrad.png
Note that proper Imagemagick syntax reads the input first.
ADDITION:
Given your new information in your comment, try this:
convert grad.png -crop 16x16 -resize 16x8 -gravity northwest -background none -extent 16x16 -append newgrad.png
Change the background color as desired and the gravity setting as desired for positioning.
I have image.png in truecolor,
palette.png (N colors, where N>256) or text file, where list RGB color palette.
How to get a picture with this palette?
If I use imagemagick:
convert image.png -remap palette.png remap_image.png
It does not work.
convert image.png -map palette.png remap_image.png
Gives a very bad quality. The image is very noisy. File size is bigger than before.
GIMP gives best quality:
Сonvert image to indexed color > use custom palette
But GIMP is GUI. I need to convert a lot images in the console without running the gimp and X.org.
Using a shared palette across multiple images requires a carefully crafted palette. If you don't take great care when using the palette of a single image across many images, the result will be poor.
This needn't be complicated though. If you have accesss to the GIMP (or other tool) which supports truecolor graphics, you can create a large image and fit all of the smaller images into it, then quantize the image to N colors, then use that palette as the source.
you should be able to closely mimic GIMP's behavior in the console using ImageMagick
Once you've got a truecolor image with all the colors you want to quantize,
# Create an 8-bit png from our source, with a 235-color palette as an example.
convert truecolor_source.png -colors 235 palette.png
# Create an 8-bit png from an arbitrary image and use the palette in palette.png
convert sample.png -map palette.png output.png
There are a number of options for down-sampling colors, like dithering. See the ImageMagickv6 example page for an excellent overview with example pictures and code.
Although I still don't exactly understand what you want to do, your currently most recent comment ("Yes, from RGB to palette will set independently. Need set correct quantity of colors"), it sounds like all you want to do is set a strict limit on the amount of colors of a bunch of images, but they don't need to use the same palette.
In that case, the solution is very simple:
convert sample.png -colors 135 output.png
Try playing with the quantization options if the result isn't to your satisfaction.
If the output image is too large for your liking, you can experiment with the -quality option.
If this still isn't satisfactory, please try to explain your goal in a more detailed manner.
Good luck!
cat photo.png | pngnq -s 1 > photoindexed.png
I tend to get good results with the "-remap" (single imge) or "+remap" (multiple images) functions in combination with "-colors". Read up on those functions here. Note that "with "-remap" you provide IM with the final set of colors you want to use for the image, whether you plan to dither those colors, or just replace the ones with their nearest neighbours.", meaning just remapping/replacing might not look good enough, as colors from the input image are simply replaced by those from the palette image. Some form of dithering will be necessary to distribute pixel color conversion errors throughout the output image, because not all colors in the palette match those of the input image.
I'd suggest you use the "-colors N" option for that. This will reduce your output image color count to a maximum of N. By default ImageMagick uses "-dither Riemersma" for this implicitly when you specify "-colors N". The are also other dithering options available.
I have a number of input images that contain multiple smaller images, all of them in a single row. All the contained images are the same size. So, for example, the image input.png may be 480x48 and contain 10 48x48 images, all in one row.
Using the imagemagick convert tool (or any other tool supplied with the defaul imagemagick suite), I want to write a bash script that takes an input image, the number of images to cut, and then cuts them all into individual images.
The user interaction i can do, but I've not been able to get convert to do the actual cutting. Can anyone suggest something? From reading the manual pages, i think this should work:
convert 'input.png[0x0+48+48]' output.png
but I get an error:
convert: no pixels defined in cache
tb_icons_l.png' #
magick/cache.c/OpenCache/3572.
convert: No IDATs written into file
1.png' #
coders/png.c/PNGErrorHandler/1391.
Any ideas?
I would do it like that:
convert input.png -crop 48x48 +repage +adjoin output_%02d.gif
Read more at Tile Cropping, in ImageMagick documentation.
I believe you've got the position and size swapped. Try:
convert 'input.png[48x48+0+0]' output.png
The third image would be:
convert 'input.png[48x48+96+0]' output.png
Or
convert 'input.png[48x48+0+96]' output.png
I want to use CSS sprites on a web site instead of separate image files, for a large collection of small icons that are all the same size. How can I concatenate (tile) them into one big image using ImageMagick?
convert works much better than montage. It arranges images vertically or horizontally and keeps png transparency.
convert *.png -append sprites.png (append vertically)
convert *.png +append sprites.png (append horizontally)
From the page you linked, 'montage' is the tool you want. It'll take a bunch of images and concatenate/tile them into a single output. Here's an example image I've made before using the tool:
(source: davr.org)
You are looking for:
montage -background transparent -geometry +4+4 *.png sprite.gif
I like this script for automatical sprite/css generation.
"Building CSS sprites with Bash & Imagemagick"
article copy in Waybackmashine https://web.archive.org/web/20150529041037/http://jaymz.eu/blog/2010/05/building-css-sprites-with-bash-imagemagick
script copy http://blog.kupriyanov.com/2011/01/solvedbuilding-css-sprites-with-bash.html