Here you will find all of the information (appropriate links (including Dropbox folder links for homework), notes, reminders, etc.) for Photoshop 101 (Photoshop Basics for Artists) Week Two.
HOMEWORK RESULTS FROM WEEK 1 (total 2 points):
EG: 2
GK: 2
HB: 2
JL: 2
KT: 2
KB: 2
MS: 2
NOTE: Please respect the work, rights, and privacy of participating artists. You may view the uploaded homework efforts from the class within the Dropbox folder, but you may not download or manipulate their work in any way. Anya and I will be downloading uploaded homework or classwork images when needed/appropriate, but we will never share anyone’s images outside of the class without express permission from the author. All files in the Dropbox folders will be deleted at the end of the course. In addition, please know that classes will not be recorded to respect each participant’s learning experience.
If there are files required for the week’s homework, then they will be available in a folder called “WeekX_Resources” in the appropriate week’s folder. You will need to download to files in this folder to complete the week’s homework. However, please be sure not to remove or add anything to this folder.
Again, as to file naming: Moving forward, images should have the following format (where fields are appropriate):
Name_Title_Size-in-inches (height first)_Medium (if applicable)_Price (if applicable)_SMALL/MED/LARGE-or-PPI
Today we will review the homework and some info from the last class, cover a relatively new file format WebP, file naming, goals and controls (e.g., Save As/Export), the Helmholtz–Kohlrausch effect, Color Modes (RGB, CMYK, and Grayscale,) Image Resampling, and Color Bit Depth (8, 16, and 24 bit.)
Each color on top has approximately the same luminance level and yet they do not appear equally bright or dark. The yellow (second from the left) appears to be much darker than the magenta (right-most). However, when the top image is converted to grayscale, we have the image on the bottom–a single shade of gray.
Some definitions for today:
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Image Size Resample
This is an option in the image sizing window that, when checked, allows the changing of the actual number of pixels in the image. Resizing without resampling keeps the pixel count fixed (you’re just changing how pixels map to inches/cm). Resampling adds or deletes pixels. -
Color Mode
Color modes or image modes are the basis for the representation of a pixel’s color value. These modes determine how an image will be represented on screen or in print. For instance, use CMYK color mode for images in a full-color print brochure, and use RGB color mode for images in web or e-mail to reduce file size while maintaining color integrity.
Different color modes:
1. RGB mode ((Red-Green-Blue) This is a universal mode that your desktop and camera use. RGB stands for Red, Green, and Blue, so it manages colors via configurations/combinations of red, green, and blue. This mode has the largest gamut of the modes we discussed.
2. CMYK mode ((Cyan-Magenta-Yellow-Black) The next most common mode. This mode manages color in a way that is conducive to common printing processes. CMYK covers fewer colors because subtractive inks cannot reproduce the full range of additive RGB light.
Fun Fact: The K in CMYK is known as the Key, because it’s the key plate that prints all the detail in a printed image. In printing, Cyan, Magenta, and Yellow plates are properly aligned with the Key plate.
3. Grayscale mode This is the most basic mode, consisting of a single channel that maps values to grays, from black to white.
WHEN CHANGING MODES:
You can change an image from its original mode (source mode) to a different mode (target mode) by going to IMAGE>MODE. Keep in mind that when you choose a different color mode for an image, you permanently change the color values in the image. For example, when you convert an RGB image to CMYK mode, RGB color values outside the CMYK gamut are adjusted to fall within the gamut. As a result, some image data may be lost and can’t be recovered if you convert the image from CMYK back to RGB.
TIP: Before converting images, it’s best to do the following:
• Do as much editing as possible in the original image mode.
• Save a backup copy before converting. Be sure to save a copy of your image that includes all layers so that you can edit the original version of the image after the conversion.
• Flatten the file before converting it, as the interaction of colors between layer blending modes changes when the mode changes. Not always mandatory, but flattening avoids unpredictable blending shifts between modes. (We will get to this next week!)
- Color Bit Depth
Bit depth quantifies how many unique colors are available in an image’s color palette in terms of the number of 0’s and 1’s, or “bits,” which are used to specify each color. This does not mean that the image necessarily uses all of these colors but that it can instead specify colors with that level of precision. For a grayscale image, the bit depth quantifies how many unique values are available. Images with higher bit depths can encode more shades or colors since there are more combinations of 0’s and 1’s available.
Every color pixel in a digital image is created through some combination of the three primary colors: red, green, and blue. Each primary color is often referred to as a “color channel” and can have any range of intensity values specified by its bit depth. The bit depth for each primary color is termed the “bits per channel.” The “bits per pixel” (bpp) refers to the sum of the bits in all three color channels and represents the total colors available at each pixel. Confusion arises frequently with color images because it may be unclear whether a posted number refers to the bits per pixel or bits per channel. Using “bpp” as a suffix helps distinguish these two terms.
Most color images from digital cameras have 8 bits per channel, meaning each primary color channel (red, green, and blue) can represent 2^8, or 256, different intensity values. When all three channels are combined at each pixel, the total possible colors are (2^8)³ = 16,777,216—often referred to as “true color.” This is why an 8-bit-per-channel RGB image is also described as 24 bits per pixel (8 bits × 3 channels).
- If X refers to bits per pixel, the number of possible values is 2^X.
- If X refers to bits per channel (for RGB), the number of possible values is (2^X)³.
TIP: The available bit depth settings depend on the file type. Standard JPEG and TIFF files can only use 8-bits and 16-bits per channel, respectively.
HOMEWORK: Due in Dropbox by Wednesday, Oct. 9th
Homework: Locate a “high-res” color version of a favorite masterwork online and save it to your desktop. Using that file, generate two grayscale versions—one should be an “unweighted” desaturation and the other, a curated, weighted version that you feel best compensates for the loss of hue and chroma (saturation) contributions. Upload both to the homework folder as “high quality” jpegs in the ballpark of 200ppi@5x7". This is worth 4 points!!!
Bonus Scenario: You have been invited to participate in an upcoming book that explores how artists might reinterpret the value structure of their own color paintings, drawings, or photographs if they were limited to grayscale. The publishers request two images of a single work, one with a simple unweighted desaturation and one with an artist-curated, weighted desaturation. Both files should be print-ready, high-res (300ppi@8x10"), but small enough to be sent via email. Please upload the two files you would send, formatted and appropriately labeled to this week’s homework folder. This bonus is with 2 points!!!
DROPBOX LINK: Dropbox
Great question once put forward: Philippe asked, “Does it really make any difference if you save something at 5x7 inches @72ppi or 1.68 x 1.207 300ppi as they would seem to be the same?”
In most cases, these files could be considered synonymous (if @72ppihe pixels are exactly the same) in that if you open the two images on screen, you will see absolutely no difference between them. However, there is a difference if you try to drag and drop them into a word processor.
For example, here are two copies of my painting Paradise. One is saved at 5x7" @ 72ppi, while the other is 1.68x1.207" @ 300ppi. Either way, the pixel dimensions on both are 362x504. They are so alike that even this program discourse kept displaying the same image.
This is how they appear, though, when dragged into a Word doc:
As you can see, one becomes much smaller than the other. The issue is how some software treats the measurements. (Page-setting software like InDesign does the same thing.) In both cases, the target environment measures things in real-world units (centimeters or inches), so it uses the dpi metadata to decide how to convert your image’s pixel dimensions to real-world dimensions. For example, a 600x600-pixel image at 300 dpi will appear on the page at 2x2 inches.
By contrast, most screen-based environments (Photoshop, the web, etc.) measure things in pixels, so no conversion is needed: each pixel in your image simply occupies one pixel of your screen.
So, if you’re preparing an image for print on paper or other physical media and you’re asked for a specific dpi (which will usually be 300), you should stick to it to ease the workflow at the print end. (Of course, a page designer can always convert your 72dpi image to 300dpi without losing anything, but why make things difficult?) Note that this only ever applies if your image is going to be placed on a page (for example, in a magazine or book), which is why it so rarely makes a difference. If you’re just printing photos full-page (either on your own printer or sending them off for photographic prints), the dpi will make no difference.
Herb asked, “Is RGB in Photoshop the same or equivalent to sRGB.?”
Honestly, at first I thought it would likely be the same thing, but it turns out that Photoshop’s RGB Color Mode isn’t a single fixed color space—it requires a profile, like sRGB or Adobe RGB. Adobe also developed their own wide-gamut profile, known as Adobe RGB.
While both Adobe RGB and sRGB have advantages and drawbacks, Adobe RGB provides more flexibility for editing and switching profiles because it covers a wider range of colors (a larger gamut). A photograph taken in Adobe RGB mode can be safely converted to sRGB. By contrast, sRGB images cannot be expanded into Adobe RGB because those extra colors were never captured in the first place.
Key point for artists: Photoshop’s “RGB” mode does not automatically mean sRGB—it depends on your chosen working color profile (sRGB, Adobe RGB, or even ProPhoto). If you don’t set one, Photoshop often defaults to sRGB, which is safest for web use.
You can learn more about the differences here:
https://www.viewsonic.com/library/creative-work/srgb-vs-adobe-rgb-which-one-to-use/
Some software mentions: