racket: manipulating jpeg files
I'm trying to manipulate jpeg files in racket lang. I failed to find any racket library with good cross-platform support (linux, mac osx, win10). Does exist any?
Actions I want to perform are read exif, scale images and store it to database.
There are several external libraries that you can use to do image (and video) manipulation. However Racket actually comes bundled with a good amount of image manipulation tools (that work on jpg, png, bitmap, etc.). Most notably the pict library and the racket/draw library. I highly recommend you use those for most standard image manipulation tasks (e.g. scaling, transformations, etc.). You can even use the sql library (which also comes with Racket to store your files to a database.
If you want to use the racket/draw class, you can create a bitmap% object which allows you to save to and load from files. You can also use a bitmap-dc% to do basic drawing operations.
The pict library is a nice functional API for image manipulation. And you can use the bitmap function to get a bitmap from a file, as well as convert a bitmap% object to a pict object. The pict->bitmap function lets you go the other way, converting a pict object to a bitmap.
- Matching pair-wise columns from left to right across rows in one dataframe to another dataframe and adding new columns with matching values
- color mapping in geom_conn_bundle not showing correctly
- Print R package startup message AFTER automatic package conflict messages instead of before
- Summing a set of R dataframe rows (column-wise), while retaining the first n columns
- Added variable / partial regression plots for groups in an interaction?
- how to make a topoplot in R with coordinates variable distribution
- List of all functions in base R?
- Plotting multiple plots for different initial conditions in one graph
- Printing repetitively on the same line in R
- Generating UI/Server based on initial selection
- Subset dataframe based on pickerInput
- How to let user pick the data in R-shiny?
- Couldn't show my simple bar charts separately on Shiny R dashboardBody
- How to programmatically filter contents of a second shiny app displayed via iframe
- How to select specific interesting groups for the boxplot in R Shiny app?
- Crosstable and Plot grouping with reactive values
- Is there a way to make multiple Shiny picker inputs where the selections must be disjoint?
- Delay/avoid duplication of shiny server side functions until after credentials
- Predictions only returns value "1"
- How to display a busy indicator in a shiny app?
- Append doesn't work when writing to CSV in R
- Changing the start date of a gantt chart in DiagrammeR
- Check for installed packages before running install.packages()
- Compare two columns element-wise
- For loop is several times faster in R than in Python using the rpy2 library
- Setting a flag based on two samples' dates
- How to bring pop-ups for long text string selection items forward in front of modal they are rendered from when using virtualSelectInput()?
- R data.table update join by reference the, but updating the RIGHT table
- How to add tooltip labels in R Sparkline?
- How to draw circles (circular dots) from linetype in ggplot2