Re: Gimp 64 Bits
Hedy Madrid
I personally thought (!) that a TIFF coming in at 16 bit will be treated in 16 bit and a JPG will always be treated in 8 bit. When you export the TIFF (actually the XCF) into JPG it will be scaled down to 8 bit.
It will always do that when exporting to JPEG because the popular JPEG implementations only support 8-bit precision (though the JPEG standard allows for higher precision). What happens when you export to TIFF or PNG is up to you.
Absolutely. The file going from dt/lightroom to GIMP is an intermediate file, i.e. it is not the final file. Intermediate files should not lose data and should be fast to read/write, so use 16-bit TIFF, uncompressed if possible. You can then export the file from GIMP in 8-bit precision if you like.
But a significant reason to consider floating point is that the image storage convention, black=0.0, white=1.0, allows an edit that causes particularly white to go past 1.0 to actually retain a meaningful value, rather than be clipped as it would be in 8- or 16-bit integer format.
The instructor says that 16 bits is overkill in most cases and you should only use it where you get color banding (artifacts) from adjusting hues and tone curves. Otherwise, you are slowing your machine down and bloating your file sizes for no reason.
I think this has more to do with ensuring the authenticity of the information and avoiding manipulated pictures and montages. See the World Press Photo and McCurry controversies in the past few years.
The flatpak build is new and has known limitations, though it will likely provide faster updates, following GIMP releases closely.
Therefore choose your installation medium according to your needs.
The flatpak link above should open your software installer and prompt you to install GIMP. Yet it may not work out-of-the-box on some platforms since the flatpak technology is new. If that is the case, ensure flatpak is installed and if clicking the link still does not prompt to install GIMP, then manually install by command line:
Once installed, it will be made available exactly the same way as other applications (menus, desktop overview, or any specific application launch process used by your desktop).
If this is not the case, we suggest to report a bug to your desktop or distribution asking for proper support of flatpak. In the meantime, you can still run it by command line (not as the recommended method, only a workaround):
This installation will also provide regular update. You don't have to come back on this page and install again (it will not work!) when a new version of GIMP is released. Instead if your distribution and/or desktop has a good support for flatpak, it should propose to perform updates.
Once again, if your distribution does not have proper support, you can always fall back to using the following command line:
Third party packages are not officially supported by the GIMP project. Therefore you should report issues to the packagers first, before reporting to the GIMP team. We only list some of these package systems here because they are widely used FLOSS projects, though we won't list projects providing very outdated versions.
An easy way to compile and install GIMP and other great Free software on your Mac is by using Macports. The installer allows you to choose from a large directory of packages. To install gimp using Macports, you simply do sudo port install gimp once you have Macports installed.
Homebrew is similar to Macports and provides packages (aka formulas) to install, either by compiling them from source or by using pre-made binaries. There are indications that there is now a formula for GIMP, installable with: brew tap homebrew/cask && brew install --cask gimp.
Fink is a package repository that offer mostly precompiled binaries. It provides the apt-get command known to e.g. Debian and Ubuntu users, and installing GIMP is as easy as sudo apt-get install gimp once you have installed the Fink installer.
If there's no binary package, then fink install gimp will compile GIMP from source.
Disclaimer: we haven't been able to determine if it is possible to install or build recent GIMP from Fink. Last we checked, GIMP 2.6.12 appears to be the most recent GIMP package that is offered there.
GIMP on the Microsoft Store is the same as the direct link installer. If you wish to install through the store, we recommend using the provided store link as our team cannot vouch for third-party packages of our code.
I know one problem with gimp. You can get alpha to work with color only. You hit calc alpha in texture menu to see the alpha. But as soon as you hit NOR, it will bump the original image and ignore the alpha. I do not know yet of a quick way to fix this.
When exporting an image, most file formats have additional options that can be set. If that is the case, then a new dialog will open after you have selected the filename and export file format. This section will document the dialogs for all export file formats.
Checking interlace allows an image on a web page to be progressively displayed as it is downloaded. Progressive image display is useful with slow connection speeds, because you can stop an image that is of no interest; interlace is of less use today with our faster connection speeds.
GIF comments support only 7-bit ASCII characters. If you use a character outside the 7-bit ASCII set, GIMP will export the image without a comment, and then inform you that the comment was not saved.
You can set the delay, in milliseconds, between frames if it has not been set before. In this case, you can modify every delay in the Layer Dialog. Note that some operating systems and applications may override with a lower frame rate due to computer speed, performance, or other technical limitations.
If Lossless is not checked, this value determines the quality of the image compression. 100 provides the best quality image and lowest compression, while 0 provides the highest compression and worst quality image.
JPEG files usually have an extension .jpg, .JPG, or .jpeg. It is a very widely used format, because it compresses images very efficiently, while minimizing the loss of image quality. No other format comes close to achieving the same level of compression. It does not, however, support transparency or multiple layers.
The JPEG algorithm is quite complex, and involves a bewildering number of options, whose meaning is beyond the scope of this documentation. Unless you are a JPEG expert, the Quality parameter is probably the only one you will need to adjust.
When you save a file in JPEG format, a dialog is displayed that allows you to set the Quality level, which ranges from 0 to 100. Values above 95 are generally not useful, though. The default quality of 85 usually produces excellent results, but in many cases it is possible to set the quality substantially lower without noticeably degrading the image. You can test the effect of different quality settings by checking Show Preview in image window in the JPEG dialog.
Please note, that the numbers for the JPEG quality level have a different meaning in different applications. Saving with a quality level of 80 in GIMP is not necessarily comparable with saving with a quality level of 80 in a different application.
If you have only made a few changes to the image, then re-using the same quality setting will give you almost the same quality and file size as the original image. This will minimize the losses caused by the quantization step, compared to what would happen if you used different quality setting.
Checking this option causes each change in quality (or any other JPEG parameter) to be shown in the image display. (This does not alter the image: the image reverts back to its original state when the JPEG dialog is closed.)
Arithmetic encoding is a form of entropy encoding (a lossless data compression scheme) that can be used in exporting as JPEG. Images using arithmetic encoding can be 5 - 10 % smaller. But older software may have trouble opening these images.
With this option enabled, the image chunks are stored in the file in an order that allows progressive image refinement during a slow connection web download. The progressive option for JPG has the same purpose as the interlace option for GIF. Unfortunately, the progressive option produces slightly larger JPG files (than without the progressive option).
The human eye is not sensitive in the same way over the entire color spectrum. The compression can use this to treat slightly different colors that the eye perceives as very close, as identical colors. Three methods are available:
float: The float method is very slightly more accurate than the integer method, but is much slower unless your machine has very fast floating-point hardware. Also note that the results of the floating-point method may vary slightly across machines, while the integer methods should give the same results everywhere.
Gamma correction is the ability to correct for differences in how computers interpret color values. This saves gamma information in the PNG that reflects the current Gamma factor for your display. Viewers on other computers can then compensate to ensure that the image is not too dark or too bright.
When this option is checked, the color values are saved even if the pixels are completely transparent. But this is possible only with a single layer, not with a merged composition. When a multi-layer image gets exported to a single-layer file format, there is no way GIMP could preserve the color values in the transparent pixels.
By default your PNG image is exported in a pixelformat that resembles the settings of your image in GIMP. This is usually what you want, but when you need a specific output format you can change this here to 8 or 16 bits per channel RGB or Grayscale, with or without alpha channel.
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