\n\n
Processing: Removing stars<\/span><\/h2>\n\nSubtract stars to get more from deep-sky data<\/h4>\n\n
Avoid distortion while processing by taking the stars out of the picture with free software <\/p>\n\n
<\/p>\n\n
\n\nBEFORE <\/h5>\n\n\n\n![\"\"](\"https:\/\/dj9jqhxgw9833.cloudfront.net\/uploads\/sites\/77\/2022\/09\/db377f7d-edae-43c8-bf29-fbe09f39e3be.jpg\")
The unprocessed starting image of the Flaming Star Nebula (IC 405), before the stars were removed <\/figcaption><\/figure>\n\n\n\n<\/p>\n<\/div>\n\n\n\n
\nAFTER <\/h5>\n\n\n\n![\"\"](\"https:\/\/dj9jqhxgw9833.cloudfront.net\/uploads\/sites\/77\/2022\/09\/b103bfa0-5fa3-4249-9325-12f369481cc6.jpg\")
The final processed image, with the stars reinstated <\/figcaption><\/figure>\n\n\n\n<\/p>\n<\/div>\n<\/div>\n\n
Astrophotography processing is all about the art of data control and getting the right balance between stretching data to tease out details, without going too far and \u2018clipping\u2019 it. Once the data is overstretched, delicate details are lost, or the image becomes noisy. Stars are one major obstacle during processing. They limit the extent to which data can be enhanced, as they distort or become bloated. This reduces the desired \u2018natural\u2019 appearance for deep-sky images. Software that can remove stars therefore allows the user to work on all the delicate details, without being hindered by stars. One example is the free software StarNet++. Originally developed as a PixInsight module, it\u2019s now available as a standalone program via www.starnetastro.com\/download<\/a>. StarNet++ is compatible with both CCD and DSLR data, and so a popular choice for most astrophotographer toolkits. <\/p>\n\nVersion 2 of the software was released early 2022 and includes a handy graphical user interface (GUI) that makes it more intuitive. This is the version we used to process our image of the Flaming Star Nebula (IC 405). Here we will go through the steps we took to remove the stars using StarNet++ and then use Photoshop to recover a \u2018stars-only\u2019 file which we could reapply to our fully processed nebula at the end.<\/span><\/p>\n\nTakeaway time <\/strong><\/h5>\n\nOur initial image (above) was a stacked TIFF file we labelled \u2018Start image\u2019. First, we opened this \u2018Start image\u2019 in Photoshop by clicking File > Open and navigating to our file location. We then minimised our Photoshop screen and clicked on the StarNet++ icon on our desktop. A StarNet++ GUI menu popped up (see screenshot 1). By clicking on \u2018Browse\u2019, we navigated to the location of our start image and selected it. <\/p>\n\n
Both the top and bottom boxes of the StarNet++ menu then filled with the file\u2019s path location. We amended the bottom box slightly: adding \u2018starless\u2019 next to \u2018Start image\u2019 (screenshot 1). This means that StarNet++ saved a separate \u2018starless\u2019 version of our file. We then clicked \u2018Run\u2019. <\/p>\n\n![\"\"](\"https:\/\/dj9jqhxgw9833.cloudfront.net\/uploads\/sites\/77\/2022\/09\/0f8de408-2eaa-4496-9b13-ca947f07dcef.jpg\")
Screenshot 1: the StarNet++ interface. Before clicking on \u2018Run\u2019, \u2018starless\u2019 was added to the file name to distinguish the new starless nebula from the original <\/figcaption><\/figure>\n\nA command window called \u2018StarNet console\u2019 appeared, showing the progress of the star removal. \u2018Done!\u2019 appeared on the command window once StarNet++ had finished running. A starless version of our \u2018Start image\u2019, \u2018Start image starless\u2019 now appeared in the same file location as our \u2018Start image\u2019. We opened this in Photoshop (see screenshot 2) and found the image free of all stars. This is the image we would be processing. However, before we moved on to do that, it was important that we develop a stars-only file containing just the star data minus the nebula, as we would need this at the end to reapply stars to our processed image. <\/p>\n\n
To do this, we clicked back onto the original \u2018Start image\u2019 which was the first file we opened in Photoshop. We clicked Image > Apply Image. We then selected the starless version of our image as the \u2018Source\u2019 file and selected \u2018Subtract\u2019 from the Blending dropdown menu (see screenshot 3). This subtracted our starless file from the complete data, leaving just the stars. An image containing just the stars appeared. It is important to do this step before you process the image further. <\/p>\n\n![\"\"](\"https:\/\/dj9jqhxgw9833.cloudfront.net\/uploads\/sites\/77\/2022\/09\/a3d91688-bbc6-4bbb-8e14-2caec29f28e3.jpg\")
Screenshot 2: Before moving on to processing the new starless version created by StarNet++, a stars-only file must be created to add in later <\/figcaption><\/figure>\n\nWe then clicked back onto our \u2018Start image starless\u2019 file to process our nebula without the stars. We did this by applying Photoshop adjustments including levels, colour balance, and hue\/saturation (clicking Image > Adjustments for each of these) and then adding the \u2018Dust and scratches\u2019 and \u2018Median\u2019 noise reduction filters (Filters > Noise). <\/p>\n\n
Once satisfied with our nebula, we could reapply our stars. To do this, we clicked on our \u2018star-only\u2019 file created earlier (see screenshot 3). By clicking Edit > Select All or using Ctrl + A, the star-only image is selected. We then pressed Ctrl + C to copy the file. Clicking back onto our processed, starless image, we then pressed Ctrl + V to paste our stars as an opaque layer on top. Finally, we selected \u2018Screen\u2019 from the layers blending menu (highlighted in screenshot 3) to blend the starless image with the stars, creating the final image you can see above.<\/p>\n\n![\"\"](\"https:\/\/dj9jqhxgw9833.cloudfront.net\/uploads\/sites\/77\/2022\/09\/39de12f0-e33f-4c01-bf45-7d87ce01f341.jpg\")
Screenshot 3: the stars-only file is copied and pasted as an opaque layer onto the now fully processed image of the nebula, before blending together <\/figcaption><\/figure>\n\n<\/p>\n\n
BEFORE <\/h5>\n\n\n\n The unprocessed starting image of the Flaming Star Nebula (IC 405), before the stars were removed <\/figcaption><\/figure>\n\n\n\n<\/p>\n<\/div>\n\n\n\n
\nAFTER <\/h5>\n\n\n\nThe final processed image, with the stars reinstated <\/figcaption><\/figure>\n\n\n\n<\/p>\n<\/div>\n<\/div>\n\n
Astrophotography processing is all about the art of data control and getting the right balance between stretching data to tease out details, without going too far and \u2018clipping\u2019 it. Once the data is overstretched, delicate details are lost, or the image becomes noisy. Stars are one major obstacle during processing. They limit the extent to which data can be enhanced, as they distort or become bloated. This reduces the desired \u2018natural\u2019 appearance for deep-sky images. Software that can remove stars therefore allows the user to work on all the delicate details, without being hindered by stars. One example is the free software StarNet++. Originally developed as a PixInsight module, it\u2019s now available as a standalone program via www.starnetastro.com\/download<\/a>. StarNet++ is compatible with both CCD and DSLR data, and so a popular choice for most astrophotographer toolkits. <\/p>\n\nVersion 2 of the software was released early 2022 and includes a handy graphical user interface (GUI) that makes it more intuitive. This is the version we used to process our image of the Flaming Star Nebula (IC 405). Here we will go through the steps we took to remove the stars using StarNet++ and then use Photoshop to recover a \u2018stars-only\u2019 file which we could reapply to our fully processed nebula at the end.<\/span><\/p>\n\nTakeaway time <\/strong><\/h5>\n\nOur initial image (above) was a stacked TIFF file we labelled \u2018Start image\u2019. First, we opened this \u2018Start image\u2019 in Photoshop by clicking File > Open and navigating to our file location. We then minimised our Photoshop screen and clicked on the StarNet++ icon on our desktop. A StarNet++ GUI menu popped up (see screenshot 1). By clicking on \u2018Browse\u2019, we navigated to the location of our start image and selected it. <\/p>\n\n
Both the top and bottom boxes of the StarNet++ menu then filled with the file\u2019s path location. We amended the bottom box slightly: adding \u2018starless\u2019 next to \u2018Start image\u2019 (screenshot 1). This means that StarNet++ saved a separate \u2018starless\u2019 version of our file. We then clicked \u2018Run\u2019. <\/p>\n\n Screenshot 1: the StarNet++ interface. Before clicking on \u2018Run\u2019, \u2018starless\u2019 was added to the file name to distinguish the new starless nebula from the original <\/figcaption><\/figure>\n\nA command window called \u2018StarNet console\u2019 appeared, showing the progress of the star removal. \u2018Done!\u2019 appeared on the command window once StarNet++ had finished running. A starless version of our \u2018Start image\u2019, \u2018Start image starless\u2019 now appeared in the same file location as our \u2018Start image\u2019. We opened this in Photoshop (see screenshot 2) and found the image free of all stars. This is the image we would be processing. However, before we moved on to do that, it was important that we develop a stars-only file containing just the star data minus the nebula, as we would need this at the end to reapply stars to our processed image. <\/p>\n\n
To do this, we clicked back onto the original \u2018Start image\u2019 which was the first file we opened in Photoshop. We clicked Image > Apply Image. We then selected the starless version of our image as the \u2018Source\u2019 file and selected \u2018Subtract\u2019 from the Blending dropdown menu (see screenshot 3). This subtracted our starless file from the complete data, leaving just the stars. An image containing just the stars appeared. It is important to do this step before you process the image further. <\/p>\n\n Screenshot 2: Before moving on to processing the new starless version created by StarNet++, a stars-only file must be created to add in later <\/figcaption><\/figure>\n\nWe then clicked back onto our \u2018Start image starless\u2019 file to process our nebula without the stars. We did this by applying Photoshop adjustments including levels, colour balance, and hue\/saturation (clicking Image > Adjustments for each of these) and then adding the \u2018Dust and scratches\u2019 and \u2018Median\u2019 noise reduction filters (Filters > Noise). <\/p>\n\n
Once satisfied with our nebula, we could reapply our stars. To do this, we clicked on our \u2018star-only\u2019 file created earlier (see screenshot 3). By clicking Edit > Select All or using Ctrl + A, the star-only image is selected. We then pressed Ctrl + C to copy the file. Clicking back onto our processed, starless image, we then pressed Ctrl + V to paste our stars as an opaque layer on top. Finally, we selected \u2018Screen\u2019 from the layers blending menu (highlighted in screenshot 3) to blend the starless image with the stars, creating the final image you can see above.<\/p>\n\n Screenshot 3: the stars-only file is copied and pasted as an opaque layer onto the now fully processed image of the nebula, before blending together <\/figcaption><\/figure>\n\n<\/p>\n\n
<\/p>\n<\/div>\n\n\n\n
AFTER <\/h5>\n\n\n\nThe final processed image, with the stars reinstated <\/figcaption><\/figure>\n\n\n\n<\/p>\n<\/div>\n<\/div>\n\n
Astrophotography processing is all about the art of data control and getting the right balance between stretching data to tease out details, without going too far and \u2018clipping\u2019 it. Once the data is overstretched, delicate details are lost, or the image becomes noisy. Stars are one major obstacle during processing. They limit the extent to which data can be enhanced, as they distort or become bloated. This reduces the desired \u2018natural\u2019 appearance for deep-sky images. Software that can remove stars therefore allows the user to work on all the delicate details, without being hindered by stars. One example is the free software StarNet++. Originally developed as a PixInsight module, it\u2019s now available as a standalone program via www.starnetastro.com\/download<\/a>. StarNet++ is compatible with both CCD and DSLR data, and so a popular choice for most astrophotographer toolkits. <\/p>\n\nVersion 2 of the software was released early 2022 and includes a handy graphical user interface (GUI) that makes it more intuitive. This is the version we used to process our image of the Flaming Star Nebula (IC 405). Here we will go through the steps we took to remove the stars using StarNet++ and then use Photoshop to recover a \u2018stars-only\u2019 file which we could reapply to our fully processed nebula at the end.<\/span><\/p>\n\nTakeaway time <\/strong><\/h5>\n\nOur initial image (above) was a stacked TIFF file we labelled \u2018Start image\u2019. First, we opened this \u2018Start image\u2019 in Photoshop by clicking File > Open and navigating to our file location. We then minimised our Photoshop screen and clicked on the StarNet++ icon on our desktop. A StarNet++ GUI menu popped up (see screenshot 1). By clicking on \u2018Browse\u2019, we navigated to the location of our start image and selected it. <\/p>\n\n
Both the top and bottom boxes of the StarNet++ menu then filled with the file\u2019s path location. We amended the bottom box slightly: adding \u2018starless\u2019 next to \u2018Start image\u2019 (screenshot 1). This means that StarNet++ saved a separate \u2018starless\u2019 version of our file. We then clicked \u2018Run\u2019. <\/p>\n\n Screenshot 1: the StarNet++ interface. Before clicking on \u2018Run\u2019, \u2018starless\u2019 was added to the file name to distinguish the new starless nebula from the original <\/figcaption><\/figure>\n\nA command window called \u2018StarNet console\u2019 appeared, showing the progress of the star removal. \u2018Done!\u2019 appeared on the command window once StarNet++ had finished running. A starless version of our \u2018Start image\u2019, \u2018Start image starless\u2019 now appeared in the same file location as our \u2018Start image\u2019. We opened this in Photoshop (see screenshot 2) and found the image free of all stars. This is the image we would be processing. However, before we moved on to do that, it was important that we develop a stars-only file containing just the star data minus the nebula, as we would need this at the end to reapply stars to our processed image. <\/p>\n\n
To do this, we clicked back onto the original \u2018Start image\u2019 which was the first file we opened in Photoshop. We clicked Image > Apply Image. We then selected the starless version of our image as the \u2018Source\u2019 file and selected \u2018Subtract\u2019 from the Blending dropdown menu (see screenshot 3). This subtracted our starless file from the complete data, leaving just the stars. An image containing just the stars appeared. It is important to do this step before you process the image further. <\/p>\n\n Screenshot 2: Before moving on to processing the new starless version created by StarNet++, a stars-only file must be created to add in later <\/figcaption><\/figure>\n\nWe then clicked back onto our \u2018Start image starless\u2019 file to process our nebula without the stars. We did this by applying Photoshop adjustments including levels, colour balance, and hue\/saturation (clicking Image > Adjustments for each of these) and then adding the \u2018Dust and scratches\u2019 and \u2018Median\u2019 noise reduction filters (Filters > Noise). <\/p>\n\n
Once satisfied with our nebula, we could reapply our stars. To do this, we clicked on our \u2018star-only\u2019 file created earlier (see screenshot 3). By clicking Edit > Select All or using Ctrl + A, the star-only image is selected. We then pressed Ctrl + C to copy the file. Clicking back onto our processed, starless image, we then pressed Ctrl + V to paste our stars as an opaque layer on top. Finally, we selected \u2018Screen\u2019 from the layers blending menu (highlighted in screenshot 3) to blend the starless image with the stars, creating the final image you can see above.<\/p>\n\n Screenshot 3: the stars-only file is copied and pasted as an opaque layer onto the now fully processed image of the nebula, before blending together <\/figcaption><\/figure>\n\n<\/p>\n\n
<\/p>\n<\/div>\n<\/div>\n\n
Astrophotography processing is all about the art of data control and getting the right balance between stretching data to tease out details, without going too far and \u2018clipping\u2019 it. Once the data is overstretched, delicate details are lost, or the image becomes noisy. Stars are one major obstacle during processing. They limit the extent to which data can be enhanced, as they distort or become bloated. This reduces the desired \u2018natural\u2019 appearance for deep-sky images. Software that can remove stars therefore allows the user to work on all the delicate details, without being hindered by stars. One example is the free software StarNet++. Originally developed as a PixInsight module, it\u2019s now available as a standalone program via www.starnetastro.com\/download<\/a>. StarNet++ is compatible with both CCD and DSLR data, and so a popular choice for most astrophotographer toolkits. <\/p>\n\n Version 2 of the software was released early 2022 and includes a handy graphical user interface (GUI) that makes it more intuitive. This is the version we used to process our image of the Flaming Star Nebula (IC 405). Here we will go through the steps we took to remove the stars using StarNet++ and then use Photoshop to recover a \u2018stars-only\u2019 file which we could reapply to our fully processed nebula at the end.<\/span><\/p>\n\n Our initial image (above) was a stacked TIFF file we labelled \u2018Start image\u2019. First, we opened this \u2018Start image\u2019 in Photoshop by clicking File > Open and navigating to our file location. We then minimised our Photoshop screen and clicked on the StarNet++ icon on our desktop. A StarNet++ GUI menu popped up (see screenshot 1). By clicking on \u2018Browse\u2019, we navigated to the location of our start image and selected it. <\/p>\n\n Both the top and bottom boxes of the StarNet++ menu then filled with the file\u2019s path location. We amended the bottom box slightly: adding \u2018starless\u2019 next to \u2018Start image\u2019 (screenshot 1). This means that StarNet++ saved a separate \u2018starless\u2019 version of our file. We then clicked \u2018Run\u2019. <\/p>\n\n A command window called \u2018StarNet console\u2019 appeared, showing the progress of the star removal. \u2018Done!\u2019 appeared on the command window once StarNet++ had finished running. A starless version of our \u2018Start image\u2019, \u2018Start image starless\u2019 now appeared in the same file location as our \u2018Start image\u2019. We opened this in Photoshop (see screenshot 2) and found the image free of all stars. This is the image we would be processing. However, before we moved on to do that, it was important that we develop a stars-only file containing just the star data minus the nebula, as we would need this at the end to reapply stars to our processed image. <\/p>\n\n To do this, we clicked back onto the original \u2018Start image\u2019 which was the first file we opened in Photoshop. We clicked Image > Apply Image. We then selected the starless version of our image as the \u2018Source\u2019 file and selected \u2018Subtract\u2019 from the Blending dropdown menu (see screenshot 3). This subtracted our starless file from the complete data, leaving just the stars. An image containing just the stars appeared. It is important to do this step before you process the image further. <\/p>\n\n We then clicked back onto our \u2018Start image starless\u2019 file to process our nebula without the stars. We did this by applying Photoshop adjustments including levels, colour balance, and hue\/saturation (clicking Image > Adjustments for each of these) and then adding the \u2018Dust and scratches\u2019 and \u2018Median\u2019 noise reduction filters (Filters > Noise). <\/p>\n\n Once satisfied with our nebula, we could reapply our stars. To do this, we clicked on our \u2018star-only\u2019 file created earlier (see screenshot 3). By clicking Edit > Select All or using Ctrl + A, the star-only image is selected. We then pressed Ctrl + C to copy the file. Clicking back onto our processed, starless image, we then pressed Ctrl + V to paste our stars as an opaque layer on top. Finally, we selected \u2018Screen\u2019 from the layers blending menu (highlighted in screenshot 3) to blend the starless image with the stars, creating the final image you can see above.<\/p>\n\n <\/p>\n\nTakeaway time <\/strong><\/h5>\n\n