get pixel coordinates interactively with EBimage

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Arnaud Duranel ▴ 60

@arnaud-duranel-5720

Last seen 10.3 years ago

Hello I am using R 2.13.0 & EBImage 3.8.0. I am looking for a way to obtain a pixel coordinates (as an R object) by clicking interactively on an image displayed in the GTK window using the EBImage display() function. I could use locator() after having converted the image to grayscale and displayed it using image(), but as far as I am aware I would not be able to zoom in and out and move the picture around interactively. Many thanks for your help. A. Duranel, UCL Department of Geography

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ADD COMMENT • link updated 7.6 years ago by Andrzej Oleś ▴ 750 • written 11.9 years ago by Arnaud Duranel ▴ 60

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Andrzej Oleś ▴ 750

@andrzej-oles-5540

Last seen 4.1 years ago

Heidelberg, Germany

It's possible to retrieve pixel coordinates interactively by using the function locator() in combination with the "raster" mode of display, as in the following example.

library("EBImage")

# load and display a sample image
img <- readImage(system.file("images", "sample.png", package="EBImage"))
display(img, method="raster")

# get the coordinates of parrots' eyes
x <- locator()

lapply(x, round)
## $x
## [1] 215 509
##
## $y
## [1] 232 169

ADD COMMENT • link 7.6 years ago Andrzej Oleś ▴ 750

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Andrzej Oleś ▴ 750

@andrzej-oles-5540

Last seen 4.1 years ago

Heidelberg, Germany

Dear Arnaud, many thanks for your inquiry! Unfortunately, for now EBImage is not capable of returning pixel coordinates interactively, as you would like to. However, we are aware of this shortcoming and we hope to come up with a solution to this in future releases. Nevertheless, I would strongly encourage you to upgrade to the current version of EBImage (4.0.0). It includes numerous improvements and bugfixes, does not rely on ImageMagick anymore, and introduces a new JavaScript image viewer in place of the old GTK-based one. Kind regards, Andrzej Oles EBImage Development Team On Mon, Jan 21, 2013 at 5:46 PM, Arnaud Duranel <arnaud.duranel.09 at="" ucl.ac.uk=""> wrote: > Hello > I am using R 2.13.0 & EBImage 3.8.0. > I am looking for a way to obtain a pixel coordinates (as an R object) by > clicking interactively on an image displayed in the GTK window using the > EBImage display() function. > I could use locator() after having converted the image to grayscale and > displayed it using image(), but as far as I am aware I would not be able to > zoom in and out and move the picture around interactively. > Many thanks for your help. > A. Duranel, UCL Department of Geography > > _______________________________________________ > Bioconductor mailing list > Bioconductor at r-project.org > https://stat.ethz.ch/mailman/listinfo/bioconductor > Search the archives: > http://news.gmane.org/gmane.science.biology.informatics.conductor

ADD COMMENT • link 11.9 years ago Andrzej Oleś ▴ 750

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