app
Please note that a photo doesn't always fit on a pillow format. Very often too many details are lost, unless you are crocheting with very thin yarn.
Blankets are best for photos because they offer plenty of room for image details.
Your stitch sample is important so that your crocheted piece doesn't look distorted and has the desired size at the end. Everbody has her or his own crochet and knit style, so the picture should be optimized for your way of working. The more accurate the stitch sample matches your style, the more accurate the app can calculate the number of stitches and rows needed.
The stitch sample on the banderole of a wool is always a guide only.
So notice: You can only rely on the app if you can also rely on your specified stitch sample.
A stitch sample indicates how many stitches and rows are on 10cm×10cm.
Hint: If you take the thread with you when crocheting, remember to take the thread with you also for your stitch sample.
The stitch test for Tunisian crocheters is the same as for a "normal" stitch test (please refer How do I do a stitch sample?).
It should be noted, however, that Tunisian crocheting is 1 row = back and forth row.
Thus, after, for example, 10 rows of crochet back and forth 5 rows must be entered as a stitch sample.