Adobe photoshop elements 11 pdf
The trick then is to clone out these regions from as near as possible in the frame (so that the light pollution would be similar). If the image only contained faint well spaced stars, having applied this filter would give an excellent image of the light pollution but, normally, there might be some nebula regions or bright stars which are not removed. Any processes will the only be applied to the upper layer such as the application of the ‘Dust and Scratches’ filter. In the ‘Window’ drop down menu, click on ‘Layers’ and the two layers will be seen top right. The filter ‘thinks’ the stars are dust and removes them! To achieve this, the image is duplicated (Layers > Duplicate layer) to give a second copy of the image that lies above the original.
I usually apply this with a radius of 15 pixels. Happily, rather to my surprise, Elements does include the filter that I use to achieve to remove light pollution − the ‘Dust and Scratches’ filter (Filter> Noise >Dust and Scratches). The first step that many of us need to do is to remove any light pollution in the image − but remember that the light pollution will mask any parts of the image such as faint stars or the fainter parts of a nebula that are below its brightness level, so either use a light pollution filter if one is appropriate or, even better, get to a dark site to do your imaging. When loading Adobe Elements, the ‘Expert’ mode must be selected at the top centre of the screen before the output from IRIS is loaded. These files are uncompressed and, for each pixel, 8-bits are used to encode the brightness of the three RGB colours. The stretched image produced by IRIS is saved as an 8-bit. Using Photoshop Elements to further process the stretched output from IRIS Using IRIS to produce a logarithmic stretch However, usually, a better result is achieved by bringing down the ‘View’ menu, upper left, and clicking on ‘Logarithm’ when IRIS appears to make three passes of the data to give the stretched result. When the image is loaded, IRIS automatically produces a simple linear stretch. The simplest program to use to carry out this stretch is IRIS which can be downloaded for free. The output file from DSS has to be stretched to increase the brightness of the fainter stars or nebulae. Stretching the output of DSS using the IRIS program This is caused by the light pollution within the image.
Below the stacked image is a RGB histogram of the image in which it can be seen that there is a red peak to the right of the green and blue histograms. The output from DSS often either looks very odd or shows no more stars that in one of the single short exposures that were imported into it. It then uses this data to align (using both linear and rotational movements) the frames and stack them. Having clicked on OK, the ‘align and stacking’ window appears and the default ‘Average’ stacking mode chosen.ĭSS finds stars in each frame and writes a ‘.info’ file for each frame into the folder. In this case the slider was set to 11% finding ~90 stars in each frame. A number of between 70 and 200 stars works well. These were imported into DSS and, within the ‘Register checked pictures’ box, the number of stars that it would find checked by adjusting the slider. One of the single frames to be imported into Deep Sky StackerĪligning and stacking the frames in Deep Sky Stacker ( DSS) The result did provide a nice image of the stars of the Pleiades Cluster but light pollution (and the short exposure time) hid the reflection nebula surrounding them.
Adobe photoshop elements 11 pdf iso#
A set of just 10, 30 second, frames were taken with my Nikon D80 DSLR with an ISO of 100 on a fixed tripod. I think that, in 2009, this was my very first attempt to image the Pleiades Cluster.
Processing an image of the Pleiades Cluster in Deep Sky Stacker (DSS), IRIS and Elements. There follows a simple example of its use imaging the Pleiades Cluster, M45.
Adobe photoshop elements 11 pdf free#
However, the free program, IRIS, can be used to do the initial stretch and provide an 8-bit result can be imported into Elements for further processing. This is because the output of DSS has a 16-bit depth, that is, 16 bits are used to specify each of the R, G and B values for each pixel of the image but Elements can only handle 8-bit depth values. What it cannot do is to carry out the initial stretching of the output of Deep Sky Stacker that many use to align and stack a number of short exposure images to give the effect of one long exposure. In particular, it is capable of carrying out the method I use to remove light pollution from an image. Photoshop Elements can carry out many of the processes that I use in creating my astronomical images with Adobe Photoshop.