[gnuastro-commits] master a5b8d601 05/23: Book: correcting several typos in the astscript-rgb-image section

[Mohammad Akhlaghi]

branch: master
commit a5b8d60113354e10f054052736928416b0e5e315
Author: Raul Infante-Sainz <infantesainz@gmail.com>
Commit: Mohammad Akhlaghi <mohammad@akhlaghi.org>

    Book: correcting several typos in the astscript-rgb-image section
    
    Until this commit, I did not revise the language of the new added section
    for the rgb-image script.
    
    With this commit, several typos have been corrected.
---
 bin/script/rgb-image.sh |  6 ++--
 doc/gnuastro.texi       | 90 +++++++++++++++++++++++++------------------------
 2 files changed, 49 insertions(+), 47 deletions(-)

diff --git a/bin/script/rgb-image.sh b/bin/script/rgb-image.sh
index abe35205..5255ffe7 100644
--- a/bin/script/rgb-image.sh
+++ b/bin/script/rgb-image.sh
@@ -1056,9 +1056,9 @@ TIPS:
   # First use the default options to guess the parameters.
   # Select a good sky background value of the images.
       A minimum value of zero could be a good option: --minimum=0.0
-  # Focus on the bright regions and twek '--stretch' and '-qbright'.
-      Try low values of '--qbright' tho show the bright parts.
-      Then, adjust '--stretch' for showing the fainter regions around bright 
parts.
+  # Focus on the bright regions and tweak '--stretch' and '-qbright'.
+      Try low values of '--qbright' to show the bright parts.
+      Then, adjust '--stretch' to show the fainter regions around bright parts.
       Overall, play with these two parameters to show the color regions 
appropriately.
   # (next tips only for gray background image: --grayback)
   # Change '--colorval' to select the value that separates the color and black 
regions.
diff --git a/doc/gnuastro.texi b/doc/gnuastro.texi
index 24545080..b3aae9d5 100644
--- a/doc/gnuastro.texi
+++ b/doc/gnuastro.texi
@@ -33864,16 +33864,16 @@ For more, see @option{Operating mode options}.
 @section RGB image
 A RGB (Red, Green, Blue) image is a color image generated using images from 
three different filters or channels.
 More info at @url{https://en.wikipedia.org/wiki/RGB_color_model}.
-Typical astronomical images have a very wide range of pixel values and 
generally it is difficult to show the entire dynamical range in a color image.
+Typical astronomical images have a very wide range of pixel values and 
generally, it is difficult to show the entire dynamical range in a color image.
 For example, by using @ref{ConvertType}, it is possible to obtain a color 
image.
 However, depending on the pixel distribution, it could be very difficult to 
see the different regions of the images appropriately (faint and bright objects 
at the same time).
-The reason is that images use to contain a lot of faint pixels (near to the 
sky background or noise values), and few bright pixels (corresponding to the 
center of stars, galaxies, etc.).
+The reason is that images usually have a lot of faint pixels (near to the sky 
background or noise values), and few bright pixels (corresponding to the center 
of stars, galaxies, etc.).
 As a consequence, by considering the images without any modification, it is 
extremely hard to show the entire range of values in a color image.
 To solve this issue, it is possible to perform some transformations of the 
images and then obtain the color image.
 This is actually what the current script does: it makes some transformations 
and then uses Gnuastro's ConvertType to generate the color image.
 
 This script is inspired by Lupton et al. (2004, 
@url{http://doi.org/10.1086/382245}).
-In short: it performs an inverse hyperbolic sinus (asinh) transformation of 
the images in order to change the dynamical range and show the bright and faint 
regions at the same time.
+In short: it performs an inverse hyperbolic sinus (asinh) transformation of 
the images to change the dynamical range and show the bright and faint regions 
at the same time.
 There are several parameters and options in order to change the final output, 
see below.
 A general overview of this script will be published in @url{REF}; please cite 
it if this script proves useful in your research.
 
@@ -33883,7 +33883,7 @@ A general overview of this script will be published in 
@url{REF}; please cite it
 
 @node Invoking astscript-rgb-image,  , RGB image creation, RGB image creation
 @subsection Invoking astscript-rgb-image
-This installed script will consider several images for combining them into a 
single color image.
+This installed script will consider several images to combine them into a 
single color image.
 The executable name is @file{astscript-rgb-image}, with the following general 
template:
 
 @example
@@ -33891,7 +33891,7 @@ $ astscript-rgb-image [OPTION...] r.fits g.fits b.fits
 @end example
 
 @noindent
-Some examples:
+Some examples (to obtain three appropriate images see @ref{Color channels in 
same pixel grid}):
 
 @example
 ## Generate a color image from three images with default options.
@@ -33906,24 +33906,24 @@ $ astscript-rgb-image r.fits g.fits b.fits --minimum 
0.0 \
 $ astscript-rgb-image r.fits g.fits b.fits \
                       --weights 0.9,1.0,1.1 \
                       --minimum -0.1,0.0,0.1 \
-                      --zeropoints=22.4,25.5,24.6 \
+                      --zeropoints 22.4,25.5,24.6 \
                       --contrast 3 --output color.jpg
 
 @end example
 
 This script considers three images to generate a color image as the output.
-The order of the images matter, it should be provided from reder to bluer: R, 
G, B.
-These images are internally manipulated by a series of asinh transformation 
and normalization to homogeneize and finally combine them into a color image.
-In general, for typical astronomical images, the default output is an image 
with the bright pixels in color and the noise pixels in black.
+The order of the images matters, it should be provided from redder to bluer: 
R, G, B.
+These images are internally manipulated by a series of asinh transformations 
and normalization to homogenize and finally combine them into a color image.
+In general, for typical astronomical images, the default output is an image 
with bright pixels in color and noise pixels in black.
 
-The option @option{--minimum} sets the minimum value to be show and it is an 
key parameter, it uses to be a value close to the sky background level.
+The option @option{--minimum} sets the minimum value to be shown and it is a 
key parameter, it uses to be a value close to the sky background level.
 The two important parameters that control the asinh transformation are 
@option{--qthresh} and @option{--stretch}.
 With the option @option{--grayback}, it is possible to generate a color image 
with the sky background in gray: bright pixels in color, the intermediate 
pixels in black, and the sky background (or noise) values in white.
-The black and white regions is what we call gray region.
+The black and white regions is what we call the gray region.
 It is possible to provide a fourth image (K) that will be used for showing the 
gray region: R, G, B, K
 
-The generation of a good color image is something that requires several 
trials, so we encourage the user to play with the different parameters in a 
clever way.
-After some testing, we find useful to follow the steps:
+The generation of a good color image is something that requires several 
trials, so we encourage the user to play with the different parameters cleverly.
+After some testing, we find it useful to follow the steps:
 
 @enumerate
 @item
@@ -33931,87 +33931,89 @@ Use the default options to guess the parameters.
 By running the script with no options at all, it will estimate the parameters 
and they will be printed on the command-line.
 @item
 Select a good sky background value of the images.
-A minimum value of zero could be a good option: @option{--minimum=0.0}.
+If the sky background has been subtracted, a minimum value of zero could be a 
good option: @option{--minimum=0.0}.
 @item
-Focus on the bright regions and twek @option{--stretch} and @option{-qbright}.
-Try low values of @option{--qbright} tho show the bright parts.
-Then, adjust @option{--stretch} for showing the fainter regions around bright 
parts.
+Focus on the bright regions to tweak @option{--stretch} and @option{--qbright}.
+Try low values of @option{--qbright} to show the bright parts.
+Then, adjust @option{--stretch} to show the fainter regions around bright 
parts.
 Overall, play with these two parameters to show the color regions 
appropriately.
 @item
 Use @option{--checkparams} to check the pixel value distributions.
 @end enumerate
 
+A full description of each option is given below:
+
 @table @code
 @item -h
 @itemx --hdus=STR,STR,STR,[STR]
-HDU/extensions (comma separated) for each R, G, B, K FITS images.
+HDU/extensions (comma separated) for each R, G, B, and K FITS images.
 
 @item -H
 @itemx --hdu=STR
-Common HDU/extension for the (R,G,B,K) channel FITS images (this overrides -h 
or --hdus).
+Common HDU/extension for the (R, G, B, K) channel FITS images (this overrides 
-h or --hdus).
 
 @item -m
 @itemx --minimums=FLT,FLT,FLT,[FLT]
-Minimum values (comma separated) to be mapped for each R, G, B, K FITS images.
+Minimum values (comma separated) to be mapped for each R, G, B, and K FITS 
images.
 This parameter controls the black level.
-In general, it is a good decision to set this value close the sky background 
level.
-Changing this value even slighly can dramatically change the output color 
image.
+In general, it is a good decision to set this value close to the sky 
background level.
+Changing this value even slightly can dramatically change the output color 
image.
 
 @item -M
 @itemx --minimum=FLT
-Common minimum value for the (R,G,B,K) channel FITS images (this overrides -m 
or --minimums).
+Common minimum value for the (R, G, B, K) channel FITS images (this overrides 
-m or --minimums).
 
 @item -z
 @itemx --zeropoints=FLT,FLT,FLT
-Zero point values (comma separated) of each R, G, B, K FITS images.
+Zero point values (comma separated) of each R, G, B, and K FITS images.
 Internally, the zero point values are used to transform the pixel values in 
units of Janskies.
 The units are not important for a color image, but the fact that the images 
are photometrically calibrated is important for obtaining an output color image 
whose color distribution is realistic.
 
 @item -Z
 @itemx --zeropoint=FLT
-Common zero point value for the (R,G,B,K) channel FITS images (this overrides 
-z or --zeropoints).
+Common zero point value for the (R, G, B, K) channel FITS images (this 
overrides -z or --zeropoints).
 
 @item -w
 @itemx --weights=FLT,FLT,FLT
-Relative weights for the images (comma separated values).
-With this parameter it is possible to change the importance of each channel in 
order to modify the color of the image.
+Relative weights for the images (comma-separated values).
+With this parameter, it is possible to change the importance of each channel 
to modify the color of the image.
 For example, @option{--weights=1,2,5} indicates that the B band will be 5 
times more important than the R band, and that the G band is 2 times more 
important than the R channel.
-In this particular example, the combination will be done as: 
@mymath{\rm{colored}=(1{\times}\rm{R}+2{\times}\rm{G}+5{\times}\rm{B})/(1 + 2 + 
5)=0.125{\times}\rm{R} + 0.250{\times}\rm{G} + 0.625{\times}\rm{B}}.
-In principle, a color image should recreate real colors, but this is a very 
subjetive matter and with this option is possible to change the color balance.
-It is a decision of the user to use this parameter with careful.
+In this particular example, the combination will be done as 
@mymath{\rm{colored}=(1{\times}\rm{R}+2{\times}\rm{G}+5{\times}\rm{B})/(1 + 2 + 
5)=0.125{\times}\rm{R} + 0.250{\times}\rm{G} + 0.625{\times}\rm{B}}.
+In principle, a color image should recreate real colors, but this is a very 
subjective matter and with this option is possible to change the color balance.
+It is up to the user to use this parameter carefully.
 
 @item -Q
 @itemx --qbright=FLT
-It is one of the parameters that controls the asinh transformation.
-It should be used with in combination with @option{--stretch}.
+It is one of the parameters that control the asinh transformation.
+It should be used in combination with @option{--stretch}.
 In general, it has to be set to low values.
 Then adjust @option{--stretch} to set the linear stretch (show the 
intermediate/faint structures).
 Finally, change @option{--qbright} to bring out the brighter features of the 
image.
 
 @item -s
 @itemx --stretch=FLT
-It is one of the parameters that controls the asinh transformation.
-It should be used with in combination with @option{--qbright}.
+It is one of the parameters that control the asinh transformation.
+It should be used in combination with @option{--qbright}.
 It is used for bringing out the faint/intermediate bright structures of the 
image that are shown linearly.
-In general, this parameter is choosen after setting @option{--qbright} to a 
low value.
+In general, this parameter is chosen after setting @option{--qbright} to a low 
value.
 
 @item --grayback
 By default, a black-background image is generated.
-That is, the lowest pixelvalues are shown in black.
-By using this option, a gray-background image will be generated.
-An averaged image from the three R, G, B is computed for the gray-background 
image.
-If a fourth image (K) is provided, then it is considered for the 
gray-background.
+That is, the lowest pixel values are shown in black.
+By using this option, a gray background image will be generated.
+An averaged image from the three R, G, and B channels is computed for the gray 
background image.
+If a fourth image (K) is provided, then it is considered for the gray 
background.
 See below for more options that control the color and gray regions.
 
 @item --colorval=FLT
 When @option{--grayback} is used, this parameter defines the value that 
separates the color and black regions.
 It ranges from 100 (all pixels becoming in color) to 0 (all pixels becoming 
black).
-Check the the histogram 'FOR COLOR-THRESHOLD'  with the option 
@option{--checkparams} for selecting a good value.
+Check the histogram 'FOR COLOR-THRESHOLD'  with the option 
@option{--checkparams} for selecting a good value.
 
 @item --grayval=FLT
 When @option{--grayback} is used, this parameter defines the value that 
separates the black and white regions.
 It ranges from 100 (all pixels becoming black) to 0 (all pixels becoming 
white).
-Check the the histogram 'FOR GRAY-THRESHOLD'  with the option 
@option{--checkparams} to select the value.
+Check the histogram 'FOR GRAY-THRESHOLD'  with the option 
@option{--checkparams} to select the value.
 
 @item --colorkernelfwhm=FLT
 Gaussian kernel FWHM (in pixels) for convolving the color regions.
@@ -34020,19 +34022,19 @@ With this option, the convolution will be done 
internally.
 
 @item --graykernelfwhm=FLT
 Gaussian kernel FWHM (in pixels) for convolving the background image.
-Sometimes, a convolution of the background image is necessary in order to 
smooth the noisier regions.
+Sometimes, a convolution of the background image is necessary to smooth the 
noisier regions.
 With this option, the convolution will be done internally.
 
 @item -b
 @itemx --brightness=FLT
 Change the brightness of the final image.
 By increasing this value, more brightness will be added to the color image.
-This is applied at the same time than @option{--contrast}, see below.
+This is applied at the same time as @option{--contrast}, see below.
 
 @item -c
 @itemx --contrast=FLT
 Change the contrast of the final image.
-This is applied at the same time than @option{--brightness}, see above.
+This is applied at the same time as @option{--brightness}, see above.
 The transformation is: 
@mymath{\rm{output}=\rm{contrast}\times{image}+brightness}.
 
 @item -g