Dithering a Gradient


Today’s Question: What is “dither”, and should I enable this option when creating a gradient in Photoshop?

Tim’s Quick Answer: Dithering in the context of a digital image refers to the introduction of “noise” to help prevent issues such as posterization. In the context of a gradient, dithering involves the blending of various color and tonal values to help maintain the appearance of a smooth transition.

More Detail: When you are working with a 16-bit per channel image, dithering is an unnecessary concept. However, for 8-bit per channel images dithering can certainly become a very real concern in certain contexts. The Gradient tool is a good example of when dithering can be helpful.

A gradient by definition is aimed at producing a smooth transition between one value and another. For example, let’s assume you are attempting to create a gradient that transitions from white to black over a range of 3,000 pixels, or around 10 inches assuming a 300 pixel-per-inch print resolution.

If the image containing this gradient is an 8-bit per channel image, there are only 256 shades of gray available to create a white-to-black gradient. That, in turn, means that each individual tonal value on the gradient will require just about twelve pixels. In other words, there will be a series of bands of individual tonal values defining this gradient, each being 1/25th of an inch in size.

By enabling the Dither option (available as a checkbox on the Options bar for the Gradient tool) you can help to create a smoother appearance for that gradient. Instead of having bands of various shades of gray that are 1/25th of an inch wide, you will have the appearance of a smoother gradation thanks to the dithering.

So, dithering is not necessary for 16-bit per channel images in the context of a normal photographic workflow. However, it can be very helpful to ensure that dithering is enabled for any image being adjusted in the 8-bit per channel mode.

What is PNG?


Today’s Question: We had pictures taken at our 50th and the photographer provided them in PNG file format. What is it and how do I convert to NEF or JPG?

Tim’s Quick Answer: The Portable Network Graphics (PNG) image format is actually a very good image format that I consider to be (in most respects) better than the JPEG image format. You could certainly use a variety of different software tools to create a JPEG image based on the PNG, but you may not need to. And there is no way to convert an image file such as PNG or JPEG to a RAW capture format such as Nikon NEF.

More Detail: The PNG image format supports lossless image compression and 16-bit per channel data, which is a considerable advantage in terms of image quality compared to JPEG image files. Frankly, the only real reason to use JPEG instead of PNG is to obtain a smaller file size through the lossy compression employed by the JPEG image format, which does degrade image quality to some extent.

I’m not really sure why the JPEG image format managed to gain wider adoption than the PNG file format. Part of the issue was a lack of support for the PNG format in various software applications. In fact, Adobe Lightroom didn’t even support the PNG format until version 5.

I would suggest keeping the PNG files as your “original” image format, creating other image file types only as you need them. You can use Lightroom to export a copy of the PNG files as JPEG (or other format) images, or use Photoshop or other software to save a copy of the image in a different format. But in most scenarios that probably won’t be necessary, and the PNG files will provide you with a good source in terms of overall image quality.

You could, of course, contact the photographer to see if they were using RAW capture, and if so ask if it would be possible to obtain the original RAW captures for at least your favorite images. But in many cases a commercial photographer will be reluctant to provide the RAW captures, preferring to provide only processed images to the client.

HDR and Expose to the Right


Today’s Question: Your advice [in Tuesday’s webinar presentation] to “expose to the right” on the histogram made sense, but it triggered a question immediately regarding HDR [high dynamic range imaging]. I understand your point about noise being a major reason for the advice to expose to the right. But does HDR override that advice given that the series of separate HDR frames include a wide range of exposures? I assume it does, and for the most part, I don’t see the noise problem you illustrated today.

Tim’s Quick Answer: With a good approach to capturing the original frames for your final HDR exposure, you will indeed achieve the basic benefit of “expose to the right”. This issue is less critical with HDR captures, but that is in part because of the blending of multiple exposures.

More Detail: My two key recommendations for capturing the individual frames for an HDR image address the benefits of the “expose to the right” approach, which can help maximize detail and minimize noise in the final image.

First, I recommend that for an HDR sequence you start with an exposure that is as bright as possible without losing highlight detail. In other words, your first exposure is an “expose to the right” capture for the overall scene. Of course, if HDR techniques are required this exposure will be lacking shadow detail.

My second recommendation relates to how many exposures to capture. In short, I want to capture enough images that the final image (the brightest of the sequence) shows the far left end of the histogram display at about the midpoint of the histogram display. In other words, areas of true black in the scene would be rendered closer to middle gray in the final capture.

By having this extended range of information that generally covers the full tonal range of the scene, you’ll ensure that you have good information (light) to blend together. That, in turn, will help ensure minimal noise for your final result.

Again, this isn’t a major concern for HDR imaging under normal circumstances, but by taking the approach outlined above you’ll be sure to gain the benefits of the “expose to the right” approach for your HDR captures.

Missing Panel in Photoshop


Today’s Question: While in Photoshop I was exploring the panels at the right side of the screen with attention focused on the Layers tab. I decided to click on the tab and drag it into my image area, which was fine. The only thing was, I clicked the small “x” at the top left corner of this floating panel thinking this would cause it to go back to its place at the bottom right corner of the screen. It disappeared! I have had a search through the help section of the application but have turned up blank so far. Can you please advise me on this?

Tim’s Quick Answer: You can bring back any “missing” panels in Photoshop by choosing the panel by name from the Window menu. So in this case you can choose Window > Layers from the menu to bring up the Layers panel.

More Detail: All of the various panels available in Photoshop can be found on the Window menu. The panels can be docked to the side of the main Photoshop window, left floating within the interface, or minimized to a iconic button you can click to view the full panel.

As noted in the question, if you drag a tab for a docked panel you can “drop” it elsewhere in the interface to make it a floating panel. Clicking the “X” at the top-left corner of the floating panel will close the panel. But you can bring any panel back to view by selecting it from the Window panel. Note that a checkmark to the left of a panel name on the Window menu indicates that the panel is already visible within Photoshop.

To help maintain your preferred interface arrangement within Photoshop you can save a custom workspace. Start by configuring the panels within Photoshop the way you want them. Then choose Window > Workspace > New Workspace from the menu. In the New Workspace dialog you can type a name for the workspace, perhaps using your own name or the nature of the tasks you’ll be performing with that workspace configuration.

Once you’ve saved a workspace, anytime you make changes to the panel layout you can reset to the saved configuration by choosing Window > Workspace > Reset. Note that this “Reset” command on the menu will also include the name of the saved workspace you are currently using.

Selecting Out of Gamut Colors


Today’s Question: I realize you can use soft proofing in Photoshop to see which colors in the image are out of gamut based on a particular printer profile. But is there then an easy way to select those out of gamut areas so an adjustment can be applied to only those areas, leaving all other pixels as they are?

Tim’s Quick Answer: You can actually select out of gamut colors very easily using the “Out of Gamut” sampling option available with the Color Range selection command.

More Detail: The Color Range command in Photoshop is generally used for creating a selection of a specific range of color values in an image, often to select a particular object or area within the photo. However, there are also additional sampling options available for the Color Range command, including an option to select out of gamut colors.

The first step is to configure soft proofing based on the desired output conditions. To do so, choose View > Proof Setup > Custom from the menu. In the Customize Proof Condition dialog that appears, set the applicable output profile using the “Device to Simulate” popup. Set the desired Rendering Intent (in most cases I recommend using “Relative Colorimetric”), and turn on the Black Point Compensation checkbox. Adjust any other settings as desired, and click the OK button to apply the change and enable the Proof Colors view option.

If you’d like to see a preview of which areas of the image are out of gamut, you can choose View > Gamut Warning from the menu. Then, to get started creating a selection of the out of gamut areas, you can choose Select > Color Range to bring up the Color Range dialog.

Within the Color Range dialog click the Select popup, and choose “Out of Gamut” from that popup. You can then click the OK button to close the Color Range dialog and create the selection of the out of gamut colors in the photo.

You can then, for example, add an adjustment layer to apply an adjustment to the selected out of gamut areas of the photo, or otherwise work specifically with that portion of the image.

Square Brush in Elements


Today’s Question: One of the articles in your most recent issue of Pixology details the procedure for changing the shape of a brush when used with certain tools such as the healing brush tool, etc. I often have use for a square rather than round shape brush when editing an image. My question is this: Can this adjustment be made in Photoshop Elements, on is it available only in Photoshop. And, if so, what is the appropriate procedure?

Tim’s Quick Answer: Yes, you can access a crisp square brush shape in Photoshop Elements by using the Pencil tool in conjunction with one of the selections among the Square Brushes option within the brush settings.

More Detail: The Pencil tool (rather than the Brush tool) is the key if you need a consistently crisp edge for the brush. You can think of the Pencil tool as essentially being the Brush tool with a Hardness setting that is always at 100%.

Once you’ve selected the Pencil tool in Photoshop Elements, make sure the Tool Options panel is displayed. You can simply click the “Tool Options” button along the bottom toolbar to bring that panel up. Then click the popup below the “Pencil” label at the left side of the Tool Options panel. At the top of the popup menu that appears, you can click the Brush popup to display a list of brush shape options. Select “Square Brushes” from that list, and you can then choose from the square brush shapes at various sizes.

You can, of course, then adjust the Size slider as needed. With one of the Square Brushes options for the Pencil tool the result will always be a square shape with a crisp (non-feathered) edge.

Strong Color Correction


Today’s Question: What is the best way to remove yellow from photos when the photographer did not use a flash?

Tim’s Quick Answer: There are two approaches that will likely help here. You can apply a strong shift with a Temperature adjustment, or use a technique for removing a strong color cast in Photoshop.

More Detail: The first approach would be the simpler. Very often in this type of situation simply shifting the Temperature slider significantly toward blue (away from yellow) will provide a good solution. This is possible even if the photo was not a RAW capture. For example, you could use the Camera Raw Filter in Photoshop, even with a JPEG capture. The same adjustment is also available in Lightroom and other software tools.

If the color cast is too strong for a simple Temperature adjustment, then I’d employ a helpful technique in Photoshop. Start by dragging the thumbnail for the Background image layer to the “Create a New Layer” button (the blank sheet of paper icon) at the bottom of the Layers panel.

Next, choose Filter > Blur > Average from the menu. This will process the Background Copy layer so that it contains only pixels of a single color, representing the average color for the full image. That is essentially the color of your strong color cast. You need the opposite color though, so choose Image > Adjustments > Invert from the menu to invert the color to the opposite value.

Next, on the Layers panel, click the popup at the top-left of the panel (the default value is “Normal”) and choose “Color” from that popup. This will set the blend mode for the Background Copy layer to Color, which will cause it to alter only the color (but not the tone and texture) of the underlying image.

Finally, to reduce the strength of the new color cast, reduce the Opacity setting for the Background Copy layer using the control at the top-right of the Layers panel. Start at a value of about 50%, and fine-tune from there for the best color.

With either of the above adjustments you may need to enhance overall saturation and contrast to compensate for other issues in the image. But the strong color cast should be something that can be resolved with one of the above approaches.

Screen Capture Time-Lapse


Today’s Question: Your answer about time-lapse software got me thinking about a project I’ve had on my list for a while. I’d like to record a time-lapse video of me working an image from start to finish. Can you recommend an approach for this?

Tim’s Quick Answer: I suggest using simple screen capture software, configuring the software for a reduced frame rate. You can then use virtually any video editing software you’d like to adjust the playback speed of the video to create the time-lapse result.

More Detail: The first step here is to capture your screen video, showing the editing process you have planned. I prefer iShowU HD (https://www.shinywhitebox.com/ishowu) for screen captures on Macintosh computers, and Camtasia (https://www.techsmith.com/camtasia.html) for Windows computers. These tools (or other screen capture software) enable you to specify a frame rate. You can use a relatively low frame rate (perhaps even one frame per second) to reduce the overall file size of the video you’re recording.

Regardless of the frame rate you use for capturing the initial screen capture video, you can then use video editing software to increase the playback speed for the video you recorded. The specific approach here will depend on the video editing software you’re using, but for example in Adobe Premiere Elements you can use the Time Stretch feature and in Premiere Pro you can adjust the “Speed/Duration” setting for a video clip to speed up playback.

The result can then be rendered to produce a new video at the desired speed, compressing the time you’re presenting in the video. For example, if you speed up by a factor of thirty, you can present a one-frame-per-second capture at an output rate of thirty frames per second. In other words, a process that took you thirty minutes to perform can be presented in a time-lapse video that is only one minute long.

Time-Lapse Software


Today’s Question: I’ve been doing a lot of nighttime shooting of the northern lights, and star trails. With the northern lights, I’ve been looking for a software program that will allow me to make a time-lapse video of 300-400 images.  Any suggestions??

Tim’s Quick Answer: My preference is to use video editing software to assemble time-lapse videos. This provides the additional benefit of being able to apply additional adjustments and effects to your final video. I use Adobe Premiere Pro for this purpose, but you could also employ Adobe Premiere Elements (http://amzn.to/2ovHnIH) if you prefer a more basic tool.

More Detail: With video editing software you can include still images, and specify the duration for each still. For example, if you specify that each still should be displayed for one frame, then for every thirty photos you’ve captured you’ll end up with one second of time-lapse video.

In Premiere Elements you can specify a default number of frames for each still image within the Preferences dialog. You can then import all of your still photos into your project, select them all, and add them to the timeline.

Another approach you could use in Premiere Elements would be to use the “Time Stretch” feature. With this approach you don’t need to specify a still image duration before you get started, letting the software fine-tune that setting by applying the “Time Stretch”.

You can find Premiere Elements (download version for Macintosh) here:


Note that Premiere Elements is also available for Windows, and you can also opt to purchase the software on DVD if you prefer.

Copyright Shown in Photoshop


Today’s Question: In some of your videos covering Photoshop I noticed that the filename for the image includes a copyright symbol in front of it. How do you get that copyright symbol to show up?

Tim’s Quick Answer: The copyright symbol displayed in front of the filename for an image you’ve opened in Photoshop appears automatically if the Copyright Status in metadata is set to “Copyrighted” rather than “Unknown” or “Public Domain”.

More Detail: It is important to note that the Copyright Status field that is available within Adobe applications (including Photoshop, Bridge, and Lightroom) is an Adobe-specific feature. In other words, other software tools for managing photographic images may not support this metadata field.

That said, if you’re using Adobe software products to manage your photos, you can apply a “Copyrighted” status to your photos. That, in turn, will cause the copyright symbol to appear within Photoshop if the image is opened. This might not exactly prevent someone from using a copy of your photo without permission, but it couldn’t hurt to have this additional information in Metadata.

In Lightroom you can find the Copyright Status field by choosing the Default set of metadata fields from the header of the Metadata section of the right panel in the Library module. In Adobe Bridge or Photoshop you can find the Copyright Status field by for the selected image by choosing File > File Info from the menu.

While this particular field is specific to Adobe software products, I do feel it is worth updating the Copyright Status to “Copyrighted” for all of your photos. It is worth pointing out, by the way, that an image is technically copyrighted by you the moment you capture the photo. So even if you don’t submit your images to the Library of Congress to register your copyright, you can still apply the “Copyrighted” status to the image.

Of course, if you do submit images to the Library of Congress to register your copyright, then you may want to use the Copyright Status metadata field to identify images that have been submitted for copyright registration versus those that have not yet been submitted.