AI thumbnail readability test: check the text at 168 by 94 pixels

Before you publish an AI-made thumbnail, shrink it to a small display size, about 168 by 94 pixels, and read the words with your eyes half closed. If you cannot, regenerate with fewer words, larger type and stronger contrast. Most thumbnails are viewed small, and a 16:9 image that is fine at full size can turn into noise.

Why test small

The model draws the image at its output size, and you judge it at that size. Viewers see a tiny version beside others. The test is a downscale, so it costs nothing and catches the common faults: thin letters, low contrast, three-line headlines and a face too small to read.

A script for the check

Download the result, shrink it and put it next to a few of your older thumbnails so you judge it in context.

from PIL import Image

img = Image.open("thumb.png").convert("RGB")
small = img.resize((168, 94), Image.LANCZOS)
sheet = Image.new("RGB", (168 * 3 + 40, 94 + 20), "white")
for i in range(3):
    sheet.paste(small, (10 + i * 178, 10))
sheet.save("thumb-small-check.png")

What to change when it fails

• Cut the headline to two to four words.
• Ask for a solid color block behind the text for contrast.
• Ask the text to fill at least a third of the frame width.
• Move the subject to one side so the text has a clean area.
• Generate on a text-strong model and keep quality high.

Generate a thumbnail built for the test

Ask for few words, a plain background behind the text and a large subject. The ratio is 16:9, which every Sume image model listed for text work supports.

curl -X POST https://api.sume.com/v1/images \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"ideogram/ideogram-v4.5","prompt":"YouTube-style thumbnail, the words FIX IT FAST in huge white block letters on a solid red band, a surprised person on the right, bright background","aspect_ratio":"16:9","quality":"medium"}'

Test variants, then publish

Use n: 4 for four takes, shrink all of them into one sheet and choose by legibility, not by beauty at full size. Spell-check the text by eye before upload, and keep the winning prompt and job id. For related checks, see Ideogram 4.5 size source.