I have 3 raw pictures in 16 bit depth. These pictures have all the same size and should represent a color channel each. So I want 1 raw to be red one raw to be blue and the last to be green and put them together into a tif.
If I "lose" the 16 bit depth and just get 8 bit depth for each color at this step its ok but not preferred. If there is another tool where this is possible with I'm open for it.
Kind of hard without the images, but something like this:
convert -depth 16 -size 800x600 gray:1.raw gray:3.raw gray:2.raw -combine -compress law image.tif
Specify the input files in the order R,G then B. I am assuming your red channel is in 1.raw, your green channel is in 3.raw and your blue channel is in 2.raw. Replace the filenames if not.
Set the size in the format widthxheight, and bit depth before reading.
Depending on the endianness of your data, you may need to put -endian msb or -endian lsb before you read in the files.
Specify -compress lzw to keep the output file small.
Related
convert 0101.jp2 -threshold 50% -type bilevel -monochrome -compress LZW ../0101.tiff
The resulting image looks jagged when I use the above command to convert a colored scanned text page to a black/white image (must be one bit per pixel). I want to make it of a higher resolution to look smoother. How can I use convert to do so?
Note that SO automatically converts tif image to jpg format so the output image shown below is not the same as the output image. You will need to run the convert command to get the true output image in tif.
If instead of thresholding you apply a strong contrast the gray pixels on the edge remain in a range of grays and the output is not jagged.
convert Original.jpg -sigmoidal-contrast 30 Corrected.jpg
(there are several ways to increase contrast in Magick)
I'm using ImageMagick 6.8 and I have LUT color table created in text format:
# ImageMagick pixel enumeration: 848,1,255,srgb
0,0: (0 , 0 , 0 ) #000000
1,0: (226, 226, 224) #E2E2E0
2,0: (48 , 74 , 0 ) #304A00
# ...
# few hundred more colors
Which has one colour per grayscale value (between 0 and 848 in my use case).
So, I want to convert a grayscale image to RGB one, using this LUT without any fancy gamma corrections, colour space remaps, interpolations and etc. Just straight replacement. How to do it?
Current issues start since the beginning:
Trying to convert lut.txt lut.png with various options always give me more colours than they are actually. In the LUT, there are 540 unique colours, but inspecting the generated PNG, or even identify lut.txt reports 615! This means that the LUT is not interpreted straight at all.
On the other hand, even if I succeed to read the LUT exactly, or probably avoid converting it to PNG, there comes another problem. Using -clut maps the whole greyscale range (0-65535) to the LUT, so I guess I have to normalize it first. But this screws up the greyscales input to begin with.
P.S. An answer which might be useful here is, if there is image format with bigger than 8-bit indexed palette. Then that text LUT be used as its palette and the greyscale raster as its pixel values.
In Imagemagick, use -clut to process a grayscale image with a colored look-up table image to colorize the grayscale image.
First create a 3-color color table LUT image with red, green and blue hex colors. I show an enlarged version.
convert xc:"#ff0000" xc:"#00ff00" xc:"#0000ff" +append colortable.gif
Here is the input - a simple gradient that I will colorize.
Now apply the color table image to the gradient using -clut.
convert gradient.png colortable.gif -clut gradient_colored.png
The default is a linear interpolation. But if you only want to see the 3 colors, then use -interpolate nearest-neighbor.
convert gradient.png colortable.gif -interpolate nearest-neighbor -clut gradient_colored2.png
I am trying to convert a BMP from 24 bits/pixel to 16 bit/pixel Mode in ImageMagick.
convert /tmp/a/new/37.bmp -depth 5 -define bmp:format=bmp2 /tmp/a/new/37_v2_16bit.bmp
convert /tmp/a/new/37.bmp -depth 5 -define bmp:format=bmp3 /tmp/a/new/37_v3_16bit.bmp
The result has the same 8 bit per R., per G. and per B., according to output of:
identify -verbose
What am I doing wrong? How to get 16-bit color in BMP ?
Thank you!
P. S.
-depth value
depth of the image. This is the number of bits in a pixel. The only acceptable values are 8 or 16.
http://linux.math.tifr.res.in/manuals/html/convert.html
=(
Official Documentation says (no restrictions mentioned):
-depth value
depth of the image.
This the number of bits in a color sample within a pixel. Use this option to specify the depth of raw images whose depth is unknown such as GRAY, RGB, or CMYK, or to change the depth of any image after it has been read.
convert /tmp/a/new/37.bmp -colors 256 /tmp/a/new/37_256.bmp
makes the file smaller, but visually it is the same! wth?! )))))
convert /tmp/a/new/37.bmp -colors 65536 /tmp/a/new/37_64k.bmp
same size, same visual picture.
convert /tmp/a/new/37.bmp -dither None -colors 256 /tmp/a/new/37_256_nd.bmp
a bit smaller again, but it does not look like 256-colored! bug? 256 colored 800x600 BMP is ~ 800x600x1 Bytes (without headers) ~ 480 000 Bytes. But it says ~650 000 Bytes)))) funny program))
The documentation you quoted from linux.math... is pretty old (2001) and is incorrect about -depth. The "-depth 16" option does not mean 16-bit pixels (like R5G6R5 or R5G5R5A1); -depth 16 means 48-bit/pixel R16, G16, B16 or 64-bit/pixel R16, G16, B16, A16 pixels. The "Official documentation" that you quoted (2015) is correct.
ImageMagick doesn't support that kind of 16 bit/pixel formats, so you'll need to store them in an 8 bit/channel format and live with the larger filesize.
It also appears that for images with 256 or fewer colors, it will write a colormapped image with 1, 4, or 8-bit indices. You don't have to make any special request, it'll do that automatically. Use "-compress none" for uncompressed BMP's. The current ImageMagick (version 6.9.2-8) gives me the expected 480kbyte file if I start with an 800x600 image with more than 256 colors and use
convert im.bmp -colors 256 -compress none out.bmp
ImageMagick does support a 16-bit "bitfields" BMP format while reading but I don't see any indication that it can write them, and haven't tried either reading or writing such images.
It's not ImageMagick but ffmpeg, more associated with video, can create a 16bit bmp image if you are referring to the 565 format?
ffmpeg -i ffmpeg-logo.png -sws_flags neighbor -sws_dither none -pix_fmt rgb565 -y ffmpeg-logo-16bit-nodither.bmp
That intentionally disables dithering but if you want that just omit the sws parts, e.g.
ffmpeg -i ffmpeg-logo.png -pix_fmt rgb565 -y ffmpeg-logo-16bit-dithered.bmp
If your images are inherently from an rgb565 source then it should not dither them but I'd always be cautious and inspect a few closely before doing any batch conversions.
Based on the discussion in the comments it sounds like PNG would be a good format for preserving old screenshots verbatim as it uses lossless compression but maybe that's not applicable due to use with vintage software?
I tried to use ImageMagick (v6.8.9-9 Q16) to convert a PDF containing a PNG file embedded in it to a PNG file.
The original PNG file had a transparent background. In the PDF too it appears fine. But in the PNG obtained after conversion, the area originally occupied by the PNG in the PDF has a white background. Please see the links for more clarity.
The command I ran is as follows:
convert -colorspace sRGB dice.pdf converted_dice.png
I also tried setting the -transparent white switch but it ends up taking out whites that were actually required in the final image.
Are there any extra switches or parameters to pass to convert in order to get rid of just this white background?
Kurt already explains the whole thing in great detail. So here is just how to assemble an image with ImageMagick after running it through pdfimages -png
pdfimages -png my.pdf my
This resluts in two files
identify my-0*png
my-000.png PNG 360x310 360x310+0+0 8-bit sRGB 256c 3.3KB 0.000u 0:00.000
my-001.png PNG 360x310 360x310+0+0 8-bit sRGB 256c 9.44KB 0.000u 0:00.000
my-001.png is the image labeled smask in pdfimages -list. To reassemble the image back to it's original form use -compose CopyOpacity with the ImageMagick command composite
composite -compose CopyOpacity my-001.png my-000.png my-reassembled.png
See also http://www.imagemagick.org/Usage/masking/#masks for more information.
Your approach to this task cannot work.
The command you used will convert the complete letter-sized PDF page (612 x 792 pt) into a PNG image.
However, the original size of the image embedded in the PDF page (612 x 792 pt) is 800 x 600 pixels. This can be seen by running pdfimages -list:
pdfimages -list dice.pdf
page num type width height color comp bpc enc interp object ID x-ppi y-ppi size ratio
----------------------------------------------------------------------------------------
1 0 image 800 600 rgb 3 8 image no 12 0 72 72 277K 20%
1 1 smask 800 600 gray 1 8 image no 12 0 72 72 50.1K 11%
So this is the first problem when converting the PDF page: it does not give your the correct size of the contained images.
The second, more fundamental problem however is: any image you get from converting a PDF page is the combination of all PDF objects overlayed on each other as they are from the page area. (Of course you could crop only part of the page -- but this gives you likewise the combination of all PDF objects from the cropped area...). The results of this you've encountered when you tried to convert all white pixels into transparent ones: since the originally different objects are merged into one representation of pixels, you can no longer discriminate between them as required.
You should take a different approach and use a different tool to extract the image: use pdfimages (the tool used above with the -list parameter to display image properties from the PDF's pages). As you can see, there are two images list: one is an RGB raster image, the other is a grayscale raster image, dubbed as type smask (softmask).
Here is a command to extract both images as PNG:
pdfimages -png dice.pdf dice-images
This will extract the two:
dice-images-0000.png (a color image)
dice-images-0001.png (a grayscale image)
(Note: Only very recent versions of pdfimages, the Poppler version, will let your extract the images as PNG. Within the PDF there is no such thing as PNG. There are only raster data, compressed with different methods. Older versions will only be able to extract images as PPM or PNM. This does not have any influence on what I describe below. Even if you extract PPM/PNM images, these two files can still be processed as described below...)
Below is a side-by-side, scaled-down montage of the two:
As you can see, the image itself does not have a transparent background, but a white one. (It does not have an Alpha channel.) Within the PDF format, these two images are used in combination to create transparent areas:
what appears completely black in the softmask (right) means: this pixel of the real image (left) is meant to be fully transparent.
what appears completely white in the softmask (right) means: this pixel of the real image (left) is meant to be fully opaque.
what appears in a shade of gray in the softmask (right) means: this pixel of the real image (left) is meant to be partially transparent (in line with its level of gray/black).
To combine these two files (color image and grayscale softmask) back into one PNG with transparency, you can employ ImageMagick now...
I created an 8-bit .tiff image ("test.tiff") containing a grid of 30 different color patches in the RGB color space using ImageMagick -convert.
When I convert this image into a jpeg (which is what I need) using:
convert -quality 100 -colorspace RGB -depth 8 test.tiff test.jpg
The identify -verbose command reveals that the resulting jpeg has several additional colors in the color table, each only taking up a few (1-4) pixels and residing very near the desired colors in RGB space. My assumption is that some kind of border bleeding is happening; maybe due to compression?
I don't understand why this border bleeding has occurred, especially given that it does not occur when I convert the tiff image to either a bmp or pcx image.
Thank you
By definition, JPEG is a lossy compression. The effects your experiencing are expected with the JPEG format. Setting the -quality of 100 will not have a 1-to-1 image result as tiff.
See additional answers:
Should I use JPG or TIFF for high-quality prints?
[...] because every time [JPEG] would save it it would generate some changes.
Is Jpeg lossless when quality is set to 100?
At [quality] 100, you just get the LEAST loss possible.
I don't know how you created your 30 colour swatch, or how your histogram looks, but you might try adding -dither None and -colors 30 options to your convert commands:
convert test.tiff -dither None -colors 30 ...